Of your three choices, I would go with after New Year's.
I will tell you a story. I had an uncle who received a number of free passes to WDW every year. The year he died, my aunt gave the passes to my mother for us kids so they wouldn't go to waste. They expired year end.
Well, my sister and I went Dec. 30 or 31, can't remember, for the day. It is one hour to Disney from my folks' house. It took us four hours. The last three hours on I-4 I think we went about 5 miles per hour.
There was an accident, right? Nope. We get to the Magic Kingdom and they are turning everyone around. The park is so crowded it is closed. But because we have our special tickets, they let us in.
This should have been a sign that I ought to have been willing to pay full ticket price NOT to go in, but in we go.
We....couldn't.......move. No kidding. My sister compared it to the Star Trek episode with the overcrowded planet where everyone lives shoulder-to-shoulder (the one where the crew keeps hearing this noise, and it's the collective heartbeat of millions of people pressed up against the ship).
Forget going on the rides....we couldn't even SEE the rides. The crowds were like a river, you were just pushed downstream. The maps were useless...walking around in the hub in front of the castle, there was absolutely no way to see where any of the paths to any of the lands were, because you couldn't see the ground, let alone any landscaping or any clue as to what was around you. You couldn't see anthing but the shoulder blades of the person in front of you, and that's it.
The highlight of the day was finding an out of the way building we could stand behind with enough room to move our elbows out to our sides so we could eat the sandwiches we brought.