Dear,

I will answer your question in general as the way and mode of prep for all entrance examinations is similar. It might differ from boards prep as the exam pattern and weightage is different .But having a proper knowledge for boards and jee mains will help you a lot in BITSAT

First of all we will discuss about the reference books. This is not the time for buying new books you have already bought and prepared from books but according to me just buy previous year paper books.

Now about the procedure make some routine and time gaps for your studies .Don't sit for too long take some gap between switching of subjects.

Chemistry is the most scoring subject in BITSAT . You will complete it within 35-40 mins and if don't then move ahead do not give more time to it. But for scoring good in chemistry you need to have a good knowledge of organic and inorganic chemistry because many times direct reactions are asked. Everyone has their differnent ways of remembering the reactions so choose the way that suits you and according to me from now take a chapter daily and complete all the reactions from it.

For physics i will tell you  to starts from mechanics  moving ahead to vectors ,fluids , shm and at last the atomic and nuclear physics. I would suggest HC verma for prepartion as it completes with all the concepts.

For maths i will refer to cengage as i have studied from it only . If you completes all the exercises of it then it is more than enough and in bitsat give most of your time to maths only but don't spend your time in one question .

Finally i will tell you about the revision start it before 1 month of exam .In this take a sample paper daily and attempt it as you will do in exam for 3 hours .After it take a break check your answers and clear the doubts on same day so you will not make a mistake in next one .

Finally don't freak about freaking is not the solution of anything so do your best and aim for higher as 270-280 marks will not let you to go for cs in main branch. Prepare for boards parallely as it is also most important .Many students willing to score good in entrance exams do not perform well in boards. So start your prepration  with cool mind.

Best of luck for the future ,hope you do well.