Not sure how it works, but I will tell you why I goofed!!! I have a March use year, and for some reason, we always seem to go in February. This year - I booked my 2008 points for February 2009, doesn't seem like a problem. But if for some reason we can't go last minute, or even a few months out, I'm in trouble, because I would loose those points March 1. Probably not explaining it well, but If you think you will vacation mostly in December, I would think Sept or Oct would be good for you? I could be wrong though on my logic.