Your first installment generally has to be paid before you go. Most of the college offices are closed over the Christmas-New Year period; I know Duval's closed on the 20th of December and re-opens on the 4th of January. I can't speak for the other colleges, but I'd say they do something similar.
I can only assume you're asking because you've noticed the money hasn't been taken from the account yet. Depending upon when the offer was made and when you actually authorised the college to take your money (ie they may not have been the same day) and owing to the fact that the colleges close over Christmas-New Year, it may still be some time before they actually physically take the money.
However, O Week doesn't begin until February 11 or 12 (Returners go back on the 16th), so you shouldn't worry; there's still a good forty or so days left until the college collects your fees. I wouldn't be too worried about it unless they haven't taken it two weeks before you go to university. If they haven't taken it by the end of January, that would probably be the time to start contacting them.