By the second week of November, you should see the Halloween decorations down.
As for Christmas, a lot of them are already starting to go up. Most of the Osborne Spectacle of Lights should be up by now and they are already adding some Christmas decorations in the stores.
The last MNSSHP is the 2nd, and I would expect all Halloween decorations to be down a few days after that. The Christmas special events (such as Spectacle of Lights, etc) start around the 12th, so I would expect the decorations to be fully up around the 8th-10th if not sooner.
yea, actually christmas decorations start around june and july, all the preparing. Osborne lights should be completed or almost completed, since they started a while ago. But like the other person said, the 12th is the first christmas event, so after the last halloween party they will start taking things down overnight when everyone is out and working all night every night to get christmas decorations up.
I went to MNSSHP on Halloween night 2005. It was the last night of the party that year. One of the CM's said that after the party, they started taking down the Halloween stuff that very night. I imagine that by the 10th of November, the majority of the next set of decorations will be firmly underway.
-m