When should Worldcons pay PAF?
As soon as possible! The purpose of PAF is to take one Worldcon’s surplus money and pass it on to Worldcons which can actually use it to make a better Worldcon, so it’s essential that PAF happen as early as possible. If a Worldcon is sure that it made a profit, but not sure how big it is, it’s better to pay partial PAF now and the balance (if any) later than to wait for precise numbers and not provide the funds in time to be of value.