CBSE 12th

Eligibility for B.Sc in Geography:
Candidates wishing to apply for the course need to have completed the Higher Secondary (10+2) education in any discipline or equivalent qualification, from a recognised educational board, and with a minimum aggregate score of 50%. Candidates awaiting their 10+2 or Diploma results may also apply for the course.
B.Sc in geography: Admission Process
Most institutes offering the course admit students based on the merit obtained at the 10+2 level, however, some select candidates based on their performance in a relevant entrance test. Some institutes conduct their own entrance tests for offering admission. Admission process generally varies across colleges.

You have mentioned that you are doing private coaching in Kota. That means you are already in coaching guidance. They might be given you a work schedule. Well answer to your question is from January 16 onwards you start study for your boards instead of Mains. How? I assume that you are studying in CBSE. So you have 5 subjects. Okay by January 10 date sheet will be available. Look for the first exam in that Time table. For that subject ( mostly English ) study last one week just before the exam. Now you have 4 subjects. From January 16 allot one week each to one subject. In that write as many sample paper. Correct each paper from your teacher. You need a lot of writing practice. Aim to finish each paper in 2.45 hours.
I followed this for my son only last year he got 98.2%. You will find few extra days in my plan. They are called buffer period. If some guest come to house and you miss the plan you can utilise buffer period.