It should start to pick up crowd wise on Wednesday. We have typically gone Tuesday through Tuesday and by Sunday after the crowds have really thinned out. However, I don’t know how starting the holiday festivities in Epcot before thanksgiving has affected the crowds.
We were there last year. Thursday 11/16-Black Friday.
Monday we went to Epcot and it was fine.
Main Street was chaos on Tuesday night. If you want to see Happily Ever After I highly recommend the dessert party.
We found Wednesday to be the most crowded day we have ever experienced at WDW. We were at AK. We still had a blast! Have your FPs ready to go and book a meal if you want a break from the crowds. We actually went to Sanaa for lunch and then over to AK to use FPs for sunset safari and to see Pandora at night. It was awesome.
We were there last year, if you can swing the few days before the Thanksgiving week, it was amazing!! We stayed through Thanksgiving Day. I would say it got pretty crazy starting that Tuesday. It was still fun because it’s WDW!
We were there the whole week of Thanksgiving 4 years ago. It was very manageable most of the week. We did try to brave MK Thanksgiving and it was probably one of the most packed times I have ever been in the park (and we have been Easter week and pretty much every other time during the year). We went back to MK Black Friday and did Rope Drop and honestly it was the emptiest I have EVER seen the Magic Kingdom. And it stayed that way until about lunch time. I couldn't believe it. We have never seen it that empty, even the early December trip when it was 25 degrees out! The crowds definitely picked up as the week went on, but it was a great week to go.
We go Thanksgiving week (Monday before - Monday after) every other year. We are going this year. It used to be (4+ years ago) that the Monday before and the Sunday after were absolutely perfect, low crowd days. As has been the general trend, the crowds have picked up (this could also be attributed to more people using fastpass now than 4 years ago when it was new, so fewer people are waiting in lines, resulting in a more crowded "feeling"). I will say our line waits have not changed dramatically (not including the new rides opening). Monday before is still good, Tuesday the crowds definitely increase, and Wednesday/Thursday/Friday are super crowded. However, I have found that there is wide fluctuation in which park people go to on which days (and I follow all the calendars, love touringplans, but on busy weeks there seems to be a lot of volatility in which park is crowded). I have also noticed that time of day can be a factor. If you want to see the MK fireworks, I agree do a dessert party, plan on staking out a spot well in advance (90 minutes probably if you want to be in the HUB), or catching it Monday night. I strongly recommend Park Hoppers to people going this week. If MK is bonkers, take the monorail to Epcot, or try one of the other parks (you can check wait times on the app, go to whichever park has the best looking wait times and make 4th FP for there on your way over. Make good use of EMH (if staying on property) and then get the heck out of dodge by 11:30am. On Thanksgiving day 2 years ago we rope-dropped MK (7am open I think), were at the gate by 6:30 - had FP for Mine Train and Splash... but we managed to do so much (Buzz, Tomorrowland Speedway, Peter Pan, Thunder Mtn, Teacups etc...) before it started getting crowded (around 10am the crowds were building). We were walking down Mainstreet toward the exit by 11:30 and the mass of people coming in was mind blowing. We went back to the hotel and swam (or went in the hot tub), and then spent the evening in Epcot (which was also crowded, but we weren't trying to do a ton of rides, just hanging out, having dinner etc...).
Friday is also bonkers. I found early mornings to be less crowded than late nights. One of the reasons is that usually MK is the only park open really late (2am with EMH sometimes). So all the night owls head there. Now, that being said, it still wasn't nearly as bad as during the day (still 30-40 minute waits for Space Mtn until about 1am, which is still too much for me). However, on a day when MK opens really early (7 or 8a) - the first 90 minutes I didn't see a single ride (except SDMT) with a legit (not posted by disney, which are often inflated first thing in the day, but an actual wait) of more than 20 minutes.
This is also a great week because the Xmas decorations are up, everything feels really festive, the resorts are beautifully decorated, and the weather is usually comfortable (it can be cold... we hit one year when it was 40 degrees!). It won't be really low crowds, but it is honestly my favorite time to go.
We’ve done it twice. We avoid EMH parks and rope drop each park at least once. Get at least one MK day done early in the week. Thursday we did DHS (though this was pre Toy story) and Friday we did our second MK day. I love Thanksgiving, weather is great, none of those parties cutting hours short, everything is open and at full capacity and holiday decorations are up. Have a good plan and you’ll enjoy it.