I thought someone posted on here that US/IOA decorations went up around the week of Nov 26th or the 1st week of Dec. I know in my recent searches that the parks at least IOA does Grinchmas during Dec - Jan 4th, but you should see the US/IOA website and here to see if they are doing that this year.
Question though for anyone: How bad is christmas week really in the parks? I know it will be packed, but does anyone have experience going during this time?? We are thinking of going 12/22- 12/29.