I was there last year at the same time as Mrs Bee and DangerMouse. The crowds were very light, except for the day of the Candelight. If I were going to book I would shoot for Dec. 8-12. The reason being is that you have the cast party Dec. 1, Dec. 2, then you have the Candelight Dec. 6, and Dec. 7. Those will both impact the time and the crowds. The week of Dec. 8 is still 2 weeks away from Christmas, I wouldn't think that that many people would be pulling kids out that early. I don't think many schools will be out for vaction yet either.
Last year we went before then because Thanksgiving was early. We were going to try to avoid the Candelight but, Dec. 1st was a Saturday so we chose that day as our departure day.
I think you will be fine chosing either one of those weeks but, I would chose the second week.