The online filling up of bits pilani is likely to start from January and the last date would be around third or fourth week of March. The application is not out yet so, you need to keep an eye when it is going to be out. It would be surely released by last week of Jan. After you have filled the form and submitted the application fee which ranges something around 2500 to 3000, don't forget to select your slot of examination which you have to do in April.

All the best : )