Hello aspirant

I know with the 12th board's preparation for the competitive exam is hard but if you want to achieve your goal then you can do it.

You can follow the following timetable

5.00 am - Wake up by 5.00 am and finish your daily routine and personal activities

5.15 am to 5.30 am - Practice yoga, exercise or meditation to freshen your body and mind so you can study better.

5.30 am to 6.45 am - Revise everything you have covered during the last evening/night. Revision is essential

6.45 am to 7.00 am - Have a healthy breakfast

8:30 pm to 9 pm - Dinner

9 pm to 11:30 self-study

If possible take some rest in the evening or afternoon so you will feel fresh

On Sunday  you get more time for study so study  accordingly

Good luck