Trust me, forums are the hardest to launch and sustain. For every successful forum, there are hundreds that have died a silent death.
I know what I am going to say is difficult, but you must offer something original to your visitors so that they come again & again. In addition to visiting again, they should spread the word too. I would say lure them with resources for ace-ing the IIT. They will come.
I remember when I was preparing for IIT, there was no Internet for common man's use. But the equivalent was cable TV. I had no time to watch TV. I had school and classes and slept only four hours.
Another suggestion is to get both the domains and point one to the main one.
Good luck!!