30-Day Technical Interview Prep Plan (Free Checklist)

Before

Days 1–3: measure where you actually are

1. Block one 90-minute session and solve two unseen problems with a visible timer set to 35 minutes each. No searching, no editor autocomplete. Mark each one: solved clean, solved with hints, or not solved.
2. Paste every target job description into a single document and highlight each named technology. Anything named twice goes on a study list; anything named once goes on a "recognise and discuss" list. Cap the study list at six items.
3. Create one file called `mistakes.md`. One line per failure: the problem, the wrong assumption, the fix. You will read this file more often than any textbook.
4. Ask one engineer doing the job you want for a short informational chat, and keep it to the slot you asked for — CareerOneStop, which is sponsored by the US Department of Labor's Employment and Training Administration, advises keeping informational interviews short. Ask two questions only: what the rounds are, and what candidates get wrong.

Days 4–14: core drills, 60–90 minutes a weekday

1. Two timed problems each weekday: one at 25 minutes on a topic you already handle, one at 45 minutes on a weak topic from your audit. Stop when the timer stops, even mid-function, then write the log line.
2. Solve out loud at conversational volume, sitting at the desk you'll actually interview from. A silent rehearsal is the one that collapses in the room.
3. Every seventh day, re-solve three problems from `mistakes.md` from scratch with a 20-minute cap. If one fails twice, spend a full 45 minutes on the underlying concept the next morning.
4. Twice a week, 30 minutes on fundamentals your target list names — complexity, memory model, transactions, concurrency, HTTP. Write the definitions by hand on paper; you should be able to say each in two sentences.
5. One 40-minute design exercise per week, standing at a whiteboard or on plain paper: 5 minutes on requirements, 10 minutes on high-level boxes, 15 minutes deep on a single component, 10 minutes on failure modes and trade-offs.

Days 15–24: rehearsal under observation

1. Book at least three mock interviews of 45–60 minutes with someone allowed to interrupt you. If you're in the US, you can ask a local American Job Center about a free interview workshop or mock interview to practise and get feedback (CareerOneStop).
2. Record two practice sessions and watch them back with the sound on (CareerOneStop recommends recording yourself during virtual interview practice). Count the silences longer than about ten seconds, and mark every moment you started typing before stating an approach.
3. Write a 60–90 second answer to "tell me about yourself" — CareerOneStop suggests preparing a short summary of your work background — and say it aloud five times, standing up, without notes. Then prepare five behavioural stories, each with a system, your scope and a measurable result.

Backend engineer, four years' experience, applying to a payments team

I'm a backend engineer. For the last three years I've worked on the order service at a logistics company — Java and Postgres, about forty services around us, and I owned the part that turns a booking into a set of shipment records. The work I'd point to is a rewrite of our retry handling: duplicate shipments were reaching carriers whenever a downstream timeout hit, and support was manually cancelling them most weeks. I added idempotency keys, moved retries onto a queue with backoff, and wrote the replay tool. Duplicates stopped appearing in the weekly support report, and the on-call pages for that service dropped to roughly one a month from several a week. I'm applying here because payments is the same problem with stricter guarantees, and I'd like to work where correctness is the product.

1. Prepare four questions for the interviewer: how code gets reviewed, how on-call works, how the team decides what to build, and what the first 90 days look like. Keep pay and benefits off that list — CareerOneStop advises discussing them once you've been offered the job rather than during the interview.

Days 25–28: the logistics rehearsal

1. Do one 15-minute equipment run-through at the same hour your interview is scheduled: camera, microphone, internet connection, screen share and the actual coding tool the company uses. CareerOneStop advises setting up equipment early and checking you have a good connection, closing extraneous applications and browser tabs, muting notifications, and being ready to sign on before the start time.
2. Lay out a plain-coloured top rather than a patterned shirt — patterns can distract on camera (CareerOneStop).
3. For an in-person round, pack a notebook and pen and leave the water bottle or coffee at home (CareerOneStop). Plan to turn the phone off, not to silent, before you go in.
4. Map the journey once at the same time of day and add 30 minutes. Plan to arrive early enough to complete any paperwork before the interview starts (CareerOneStop).

Days 29–30: taper

1. No new topics. 45 minutes re-reading `mistakes.md`, then one 25-minute easy problem to keep your hands warm.
2. Reread the job description once and write, in one sentence, why this team and not another. Print your questions and put them in the notebook.
3. Two nights of full sleep and a real meal beforehand. Recall degrades faster than knowledge does.

During

• Restate the problem in your own words in under 60 seconds, then say the constraints back: input size, types, whether duplicates or nulls are possible.
• Ask two clarifying questions before you write anything, and write the answers in your notebook so you can point at them later.
• Say the brute-force solution first with its time and space complexity, then say the one property you'll exploit to improve it.
• Take the pause you need. Developing an answer in your head before you respond is normal, and it's fine to take time before answering (CareerOneStop).
• Cap silence at about 20 seconds. Then say what you're weighing: "I'm choosing between a hash map and sorting first — sorting costs me the original indices."
• Write one small test case by hand before you run anything, including an empty and a single-element input.
• Trace your code line by line against that case, out loud, pointing at the line you're on.
• When you're stuck for five minutes, say so and ask for a nudge directly: "I've got a working approach at O(n²); would you rather I optimise it or move to the follow-up?"
• When corrected, say what you changed and why, rather than silently editing.
• In a design round, state your assumptions as numbers you chose — request volume, data size, growth — and label them as assumptions.
• Name the trade-off you rejected, not only the one you picked.
• Write down the interviewer's name and one specific thing they said; you'll use both in the follow-up note.
• Shake hands firmly if a hand is offered to you first (CareerOneStop) — and keep the phone switched off in your bag, not face-down on the table.
• Leave pay, holiday and remote policy for the offer conversation, however naturally the topic arises.

After

• Within two hours, while it's fresh: add the round to `mistakes.md`. The question, where you stalled, what you'd do differently, and any topic the interviewer probed twice.
• Within 24 hours: send a thank-you note by email or mail to the person who interviewed you, restating your interest in the job (CareerOneStop). Keep it to three short paragraphs and reference the specific thing they said.
• In the same note, if you got something wrong, add a two-to-four sentence correction: the fixed approach and its complexity. Don't attach a rewritten solution unless they asked for one.
• Within 24 hours: anything you promised — a repo link, a portfolio piece, a reference list, a code sample — sent in one message, not trickled.
• To the recruiter, same day: a one-line note asking when you should expect to hear back and what the next stage is.
• One follow-up, sent two or three working days after the date they gave you, in four sentences. Then a single check-in a week later. Nothing after that.
• If an offer comes, that's the point to raise pay, benefits and start date — CareerOneStop advises leaving those until the job is offered.
• If it's a no, reply once: thank them, ask which area they'd want stronger, say you'd welcome being considered again. Add whatever they tell you to `mistakes.md` and start the next cycle from the Days 4–14 block, not from Day 1.

What to avoid

Checklist

Days 1–3 — baseline

• [ ] 90-minute audit: two unseen problems, 35 minutes each, scored
• [ ] Job descriptions highlighted; study list capped at six items
• [ ] `mistakes.md` created
• [ ] One short informational chat booked, two questions prepared

Days 4–14 — drills

• [ ] Two timed problems per weekday (25 min strong topic, 45 min weak topic)
• [ ] Every session solved out loud at the desk you'll use
• [ ] Weekly: three problems re-solved from `mistakes.md`, 20-minute cap
• [ ] Twice weekly: 30 minutes of fundamentals, written by hand
• [ ] Weekly: 40-minute design exercise (5/10/15/10 split)

Days 15–24 — observed rehearsal

• [ ] Three mock interviews booked, 45–60 minutes, interruptions allowed
• [ ] Local mock-interview or workshop options checked (American Job Center, if you're in the US)
• [ ] Two sessions recorded and watched back
• [ ] 60–90 second work-background summary said aloud five times
• [ ] Five behavioural stories written with scope and result
• [ ] Four questions for the interviewer written; pay and benefits left out

Days 25–28 — logistics

• [ ] 15-minute equipment run-through on the real tool, at the real hour
• [ ] Spare apps and tabs closed, notifications muted, sign-on before start time
• [ ] Plain-coloured top laid out, no pattern
• [ ] Notebook and pen packed; no water bottle or coffee for in-person
• [ ] Phone off, not silent
• [ ] Route timed plus 30 minutes; early enough for paperwork

Days 29–30 — taper

• [ ] No new topics; 45 minutes on `mistakes.md`
• [ ] One 25-minute easy problem
• [ ] Job description reread; one sentence on why this team
• [ ] Two full nights of sleep, meal before

In the round

• [ ] Problem restated in under 60 seconds
• [ ] Two clarifying questions asked and written down
• [ ] Brute force stated with complexity before optimising
• [ ] Silence capped at ~20 seconds
• [ ] One hand-written test case, traced out loud
• [ ] Hint asked for after five minutes stuck
• [ ] Trade-off you rejected named
• [ ] Interviewer's name and one quote noted

Afterwards

• [ ] Log entry written within two hours
• [ ] Thank-you note sent within 24 hours, interest restated
• [ ] Promised links or samples sent in one message
• [ ] Recruiter asked about timeline
• [ ] One follow-up after the stated date, one check-in a week later
• [ ] Pay discussion reserved for the offer stage

Frequently asked questions

Sources

1. CareerOneStop (U.S. Dept. of Labor) — Get ready to interview | CareerOneStop
2. CareerOneStop (U.S. Dept. of Labor) — Interview Tips | CareerOneStop
3. CareerOneStop (U.S. Dept. of Labor) — Interviews | GetMyFuture | CareerOneStop
4. CareerOneStop (U.S. Dept. of Labor) — Practice interview questions | CareerOneStop
5. CareerOneStop (U.S. Dept. of Labor) — Virtual interviews | CareerOneStop
6. CareerOneStop (U.S. Dept. of Labor) — Informational interview | CareerOneStop
7. CareerOneStop (U.S. Dept. of Labor) — Interview tips | Justice-Impacted | CareerOneStop
8. CareerOneStop (U.S. Dept. of Labor) — Job Interview | CareerOneStop