I believe Im somewhat in a right place to guide you regarding BITSAT Preparation. I myself used to score between 250-260 in BITSAT Mock Tests, but ended with 319 in my BITSAT Attempt. So I believe youre currently in a very good stead with scoring around 280 in 2-2.5 hours, and can easily secure upto 350 in Final Attempt. You must just use your full test duration, have a perfect test taking strategy and proper revision before the Examination. My strategy was finishing Chemistry, Logical Reasoning and English sections with nearly 100% Accuracy in the first 45-60 minutes, followed by devoting a good time for Mathematics and Physics sections. My strength was Mathematics, hence I somewhat devoted the 60 minutes for Mathematics, followed by 30-40 minutes for Physics. In an exam like BITSAT you cant really go back and verify Questions as the Number of Questions are more and you even have a bery good scope of scoring in the Bonus Section. Hence must always keep the Last 30 Minutes for Bonus. Dont hurry and try securing atleast 10/12 Bonus Questions correctly.

The only preparation you need for BITSAT if few mock tests besides having had a very steady preparation for JEE. Do revise all formulae, refer Handbooks as Questions are somewhat direct without much Complexity. But remember Capitalize on 4 Things, Chemistry, Logical Reasoning, Verbal and Bonus Questions. There's no reason you loose out in these sections.

For more information and bitsat preparation tips do follow the link below

https://learn.careers360.com/engineering/bitsat-preparation-material/