All the things
Quote from ziggirawk:
It's unlikely that the cap will be reached, since previous attendance was in the 500s, but best bet is to pay as soon as possible.
I wouldn't hold to that logic too closely. GDQ attendance has typically doubled year-over-year, so that cap is a lot closer to reality than you'd think. For example, around half of the spots are already gone. It's better to close your spot as soon as you can to guarantee attendance.