There is a difference between holiday decorations and holiday entertainment, and there are different dates by which certain things are up. Decorations -- such as trees, wreaths, garland, etc. -- usually begin slowly appearing even before Halloween. However, since this is the year of the 60th anniversary, no one knows exactly how extensively Disney will be decorating. For example, normally the fake snow on the Winter Castle would be up before 10/31, and the Mardi Gras-inspired décor would go up in New Orleans Square by that time as well. This year there is a very strong chance that there won't be fake snow on the Castle, so we may not see that at all. As for the other decorations -- it seems evident that some of the Main Street décor might have to be removed or altered to allow for the Paint the Night parade, and I just don't know if Disney will decorate all the lands as they usually do. It seems like they really want to keep the focus on the 60th anniversary, so they will have to strike a balance between the "60th" and "Holidays." It's looking as though the Jingle Jangle Jamboree in Frontierland may be scaled back a bit too (or cancelled entirely).
Normally, the Christmas Fantasy Parade would soft open on the weekend before Veterans Day. This time around it looks like it is scheduled to start on 11/13/15 (and rumors indicate that it could end up moving to DCA, but we'll see). There are no holiday fireworks this year, it seems. I think that
Disneyland Forever will run for the rest of the year.
Haunted Mansion Holiday opens on September 11th, and will be open until early January. I suspect -- though I don't know for sure -- that It's a Small World Holiday could soft open by 11/6, if it sticks to its usual pattern.
I am guessing that Viva Navidad will return to DCA on 11/13.
It looks like Olaf's Snow Fest is returning, and probably during the holiday season, though I don't know if it will be in effect by November 13th, or after Thanksgiving, or further into December.
There are decorations at the 3 Disney hotels too. The main, large Christmas trees in the hotel lobbies usually go up about 9 or 10 days before Thanksgiving. Santa Claus doesn't appear at the hotels until Thanksgiving, nor do the Christmas carolers, so the beautiful Santa photo spot in the Disneyland Hotel might not be up until at least 11/16 or 11/17, if not later. There are gingerbread houses of varying sizes at the Grand Californian Hotel. The smallest one -- in White Water Snacks -- appears around Thanksgiving, as does the medium-sized one in Storytellers Café. The large one in the main GCH lobby was being constructed in the full week leading up to Thanksgiving last year, so people saw it being assembled, but it wasn't officially 'open' (whatever that means) until Thanksgiving day.
So, all in all, the bottom line is that a lot of decorations (whatever there is going to be this year) will be up in the parks by the second week of November, but it's hard to predict how much of the holiday entertainment will soft open and when. The hotels will most likely not begin to get decorations until the week starting 11/16.
