It would be hectic to go through all the study materials and books of 11th, while you are doing 12th studies parallelly.
What would've been better was to prepare handy notes while you were studying for 11th, which you could revise quickly.
But if you haven't prepared any such notes, it's not too late.
My suggestions would be to:
- Make a list of all the chapters in the course, in physics, chem and maths (such that you can keep track of the chapters that need to be revised)
- Create a timeline for revision of different chapters.
- Leave all theoretical stuff (like s-block, p-block) for the end.
- First, spend time on the chapters you found difficult (like integration), and leave the chapters you found easy for the end (like vectors)
- While revising a chapter, solve only the basic questions first and leave the difficult questions, and move on to next chapters. (such that you aren't stuck on the same chapter for a long time. Later when you have enough time, you can spend time on the difficult questions.)
- Make handy/short notes while revision, which could be used for quick revision in the future.
However, every person's style of studying is different, so you figure out a plan which would suit you the best.
All the best.