We went to US/IOA Thanksgiving, 2018, only the Sat the prior through Wed AM. It was WAY busier than I remember Thanksgiving 2015 being. We've not done US/IOA without staying onsite at a premier hotel and getting express passes with the room, since the early 2000s. EP makes it all SO much easier, and if you only have one day, it's a must in my opinion. Just imagine all day fastpass for all the rides except Hagrids. I still have some screen shots of wait times for the 2018 trip. and yes, I do realized wait times per the app/posted can be very , very overstated, . We go to Disney a lot, and this is usually the case, but not always, and usually they're closer to that. Like the time we did the regular queue for FoP, posted was 120 mins, actual was 100, so lower, but still a wait. So at 9:00 AM on Monday, Nov 19, 2018, HP and the FJ was 110 mins. Hippogriff was 45 mins, Hogwarts Express (from IoA) was 25 mins . (at 8:46 FJ was only 50 mins. Maybe there was a ride break down, because that seems like a big jump,) the only times I have on the US side are non HP things. 8:46 AM, Desp Me was 50 mins, Rip Ride rocket was 50, Shrek 25, . but later at 12:36PM on Nov 19, Dep Me was 80 mins, Rip Ride was 85, Shrek 50, Transformers 60. Also at 12:39 Gringotts was 100 mins.
What I noticed was an incredibly packed Diagon Alley,. Gringotts stayed high. but Gringotts (and FJ) have Awesome queues, so a little waiting is fun, and gives you time for a lot of pictures. Later in the evening, the parks clear out pretty good tho, can get things done in the hour or so before park closing. Sorry for all the numbers, but again, I was pretty surprised at the busyness of the days. we had a wonderful trip, We love US/IoA, and LOVE HP. That is amazing if you've not seen it. Were hoping to repeat the trip at fall break, but just not sure now, might have to be 2021