Hi Harsha,

As per the schedule given by Birla Institute of Technology and Sciences, the last date to fill the application form was 19th March 2018. So, you cannot apply for the examination now. It is only possible if the dates are extended. And since the correction window is open from 20th March, it is not possible to extend the dates. 

For more details you can go through the link https://engineering.careers360.com/articles/bitsat-important-dates.

All the best!!