The years we’ve been in WDW on NYE, the first two years we would arrive in Epcot around 5 PM and have dinner (sadly, we waited until very late to plan, so we were stuck with Red Dragon one year which wasn’t that good, and Chefs, which wasn’t everything we’d hoped for mostly because of the crush of guests). This way we’d have a spot for the 7:30 Illuminations. After that, I’d leave the wife behind and race up to the MK for Holiday Wishes and I’d have no trouble getting into the MK at 8:15. (The second year I took a taxi between Epcot and the Contemporary instead of the monorail)
I’d leave the MK and return to Epcot to hold our midnight spot by about 9:30 and then DW could shop. I think one year when I was returning to Epcot I was able to squeeze in a ride on Spaceship Earth because it had maybe a 5 minute wait.
The third year we were in WDW for NYE, we just stuck with the MK, so we had dinner at Contemporary Steakhouse (the last year it was open) and headed over to the MK at about 8 for Holiday Wishes and also to stay straight through midnight.
For this, I staked out a spot just in front of the flagpole circle tree and on the right as you face the castle.
We did not even bother with the parks during the day and every time we lucked into not being locked out of our park of choice, even in the evening. Just don’t wait too much longer than 9:30 PM for your midnight choice. Yes, each year MK did get to Stage III closing during the day, but if you wait for the dinner exodus, you should still be able to get in between 7 PM and 9 PM.
If you think you’re going to ride easy on the busiest day of the year, be there at rope drop and be gone by noon.