The first years are in charge of hosting and I know last year some days were a little tight trying to find hosts but it always worked out and I would say the interviewees had a great time (we liked to take people out or do whatever instead of having you sit there and watch us study!)
Occasionally you will come when there is an exam and in that case some of the duty falls to 2nd and 3rd year students (2nd years have very little time, well depending on the rotation) but have no fear because it usually works itself out at the latest one week ahead of time, but do call if you are concerned, it is your interview and you don't need any more stress than you should already be feeling! just kidding of course! good luck, PM me if you have any specific questions, I check in every couple of days