As you can see in my signature, we have done the early November trek numerous times recently, LOL, and while not experts, I think we have a handle on decorations. Most of the MK decorations will be up by the start of the first
MVMCP. The big tree on Main Street will be up after the filming of the Christmas Day parade in early December. Usually the Osborne lights are a day or two after the first MVMCP. Last year, the lightings usually were around 6:15 to 6:30 PM
Most of the other parks will be decorated later in the month as others posted.
Resorts are the gamble however. Using Wilderness Lodge as the example, when we were there 11/07/12-11/13/12, the last night we were there, when we came back to the hotel, they were wheeling everything in to decorate, and when we awoke, the resort was unlike anything we had ever seen. Betsy spent 2 hours just snapping pics from all angles and locations, LOL. We loved it.
BUT when we returned 11/12/14 -11/18/14, later in the month than 2 years earlier, no decoration went up at almost any resort during that time, since they were focused on something else (I forget what as I type this, LOL). Not even the Gingerbread houses save Contemporary's was up by the time we left.