For boys u may have to apply it as early as possible during admission process itself, coz the hostel is inside campus and for the first year the hostel rooms are less( yeah they are coming with new building, and I donno which stage its in).
For girls, u can apply after all rounds of admission and still get an hostel rooms because the hostel for girls is some kms away from the college and then there are 2 hostel building. So no need to worry 🙂