I think people should wait until December, but each to their own i guess. The Christmas season is fun and all but every year it seems like everywhere is trying to push it back earlier and earlier into the year in an attempt to profit from it, and it's kind of diluting everything a bit too much for me. I like doing stuff like christmas shopping, markets, eating out a lot during the time and it'd get expensive to push that outside of December. That's when i start feeling more festive and decs seem to lose their meaning a little and become detached from the season if done too early. I find it nice to use putting the decs up as a way to mark the start of December and the festive period to get in the mood too.
Of course this year will be different for most. I don't plan on going out but i'll try and have a christmas season at home. I'll decorate once December hits and there will be plenty of Christmas themed snacks and movies.