I thought he needed 24-hours, not 8.
In any case, it was noon. you definitely took a long rest (or you take rests in shifts, whatever). So now it's 8pm. Not going to head toward the swamp at 8pm. So you camp in the camp overnight and leave in the morning. I guess that means Perin has time to rest and perform the 8 hour ritual before dawn the next day. I also assume you leave at dawn. So, I will post in the IC how the party departs the camp and heads for the lizardfolk in the swamp. The swamp is 3-4 days away at least (I think, I have to check my own maps).