Yes, after the first round counselling if u are alloted a seat in any nit/iiit/gfit then u have to go to an nit/iiit/central government college given in counselling centers list.
If you are given a in iit then u have to report at nearest iit.
If u don’t report on the preceding counselling day after seat is alloted then u will be eliminated from jossa counselling.
I suggest you to attend counselling after u are alloted a seat even though you don’t like the college you got. There will still be a chance to upgrade your college by selecting float option in the counselling. If u don’t attend counselling then u will not be considered for furthur rounds of counselling.
Hope this helps:)
All the best.