I have heard from recent hires (April 2010 and later) that they do try to work with your schedule in that they will put you in the next group. I would certainly try not to postpone it too many times, for several reasons...mainly, that the earlier you get to Miami, the earlier you can get in the swimming pool. Second reason is that it may not work in your favor if you postpone too many times. At some point you are gonna have to get creative about how you can get to the interview while on work duties...wink, wink!!