Hello Anusha, 

You need to book slot for PESSAT exam. And the slot booking process will started from 16 april-2018(for B. tech course). You will have to book both test centre and exam date. As it is first -come-first-serve basis and changes cannot be made once slot booking is done.. Be careful and attentive while booking you 3rd slot. 

Thanks for being at careers360.

All the very best for your future!!