For us it doesn’t matter too much. My DH and I tend to take a trip of 10-12 days, so we plan NOT to go into parks on saturdays. Just feel that is a crowded day. But that was the first day for our DS and DDIL, so I would think they would want to hit a park. But between flight times and a dinnner at Ohana, they could only get into a park for a couple of hours. And I’m guessing EVERYBODY would be at Epcot.
But of course as mentioned in another thread, DS may be coming in a day early, so no more problems time wise.