Preparing for JEE MAINS and JEE ADVANCED completes 75% task for getting into bits and remaining 25% depends on our speed.
Just practice bitsat book for last 1month and the speed increases.I guarantee you and you will see the result in exam.
I have been in the college for 1month and had an awesome experience.
So just don’t panic and solve the easy and medium level questions which are enough for exam.
Good luck for your BITSAT.