The decorations are up & HM & IASW are Christmas themed the first week in November. The fireworks & snow are usually about that time, as well as the tree, cookie decorating, etc. The next week you'll have Santa, carolers, etc., and the parade usually starts on Thanksgiving day. The Candlelight Processional is usually the first weekend.
Of course, these days may change slightly depending on what is going on at Disneyland at the time.