What's a good study plan and schedule for interviews while working?

For the tactics around scheduling interviews, make sure you do multiple companies at once. You'll get more practice this way, you increase your chance of getting 1+ offer, and you'll gain more leverage. Alex talks about the order in the job searching course: Order Matters.

Another idea (this is a bit of a hack): could you simply copy the playbook from existing programs that help people get tech jobs while working fulltime? Presumably, the people running these programs have done lots of deep thinking on how to efficiently study for interviews across several months.

e.g. schedule a call with Formation.dev (there's a Taro Perk for it) -- their whole program is designed for engineers working full-time to study and get into better companies. Figure out how they structure their weeks for students. Even if you decide not to do the Formation fellowship, this can educate your own study schedule (intensity and duration).

For phone screens, you can generally take them in the middle of the work day (block off your work calendar with a private block).

Onsites are awkward - You often need to take PTO to do an onsite, especially if it's just a 1-day marathon (that's how it's traditionally been done but some companies will do 2 hours each across 2 days now).

In terms of studying, you need to do it after work and probably some on weekends as well (but don't drain weekends too much as you should maintain a healthy personal life). Interview studying is best done as a consistent habit anyways (i.e. 2 hours of studying 5 days a week) instead of a "burst" activity (5 hours of studying 2 days a week).

Here's a nice related thread: "How to balance interview prep with a job?"