Ca final dt and idt may 2018

My Group 2 exam is due in may 2018

my query is whether i should refer institute's study material for DT and IDT or should should i refer CA Ravi Chawchharia sir's reference book for DT and Vineet Sodhani sir's reference book for IDT.

Also guide on paper format for DT and IDT for may 2018 exams. Whether it would be based on theory or practical.

Thank you in advance.