SNF Flex Scheduling

Can someone give me a better understanding of the rules for flex games? How soon do they have to let the fans know? I have tickets for the Dec 8th game and have a friend coming down for it, they were expecting to be leaving that afternoon to go back home. Just curious how much time we'd get to make plans around that.

12 days notice is the minimum although it could be sooner on games that are flexed. Of course Fox has to be willing to give it up too I believe.