We are going the 9th, 10th, 11th, and 12th and it is the perfect time IMHO! We start on the 9th to take advantage of any weekend only entertainment!! Fireworks are every night in December barring weather so no need to worry there! Then the 10, 11, and 12 are low low low crowds. Last two years we had walk ons those days.
Most likely the 8th will be Candlelight so I want to avoid that at all costs and the week before is Cast Member parties and the park closes early so I don't like to go then either, I need all the time I can get. Then after the 13th, it will start getting busy with people that are on break that waited and didnt' pull their kids out!!
These days are a win/win situation as far as I am concerned!!!
Andrea