Once you got a good GATE percentile and applied to different IITs, you will start getting calls during the month of April and May. Ideally IISc conduct these first and takes the cream making it easy for topper to avoid going to other places and others students a little relief from that competition.
Once you start getting the calls the first and foremost thing is to reserve your tickets. As India is a big and highly populated country you may not get the tickets and end up in traveling in mess. This happened to me and I had to stand for 30hr in general compartment for attending IITD interview. It will affect everything, test and interview and all other stuff. So as soon as you get the interview call to the nearest counter and reserve you tickets.
It is quite possible that two IITs call you on same or consecutive days and the distance between them make it impossible to appear on both places. Here you need to more calculative and know yourself and make decision. Make a safe decision because missing an IIT admission will be a real miss. It takes one more year to see all this again with new competition, so make a voice decision on which IIT you will appear. Take the following things into account.
1. How many offers you have in hand. If you have one at hand, select the best IITs among the choices.
2. Consider your competing skill the higher the IIT in rank the higher the competition and test.
3. Don’t underestimate other IITs and feel bad in making a decision.
Once you make decision, be happy for that and think that is best for you. Go ahead and appear for the written test and interview. Forget about you have left, you can do better at any IIT, because IIT is an IIT.
Donot forget to cancel the reserved tickets to some IIT, if you are not going there. Enjoy local travel with that 😉
Do check the travel list and printout. I will be helpful when packing and make sure you did not miss something which was really important.