It can be a transition to Christmas decorations once Halloween is gone - moving through pumpkins (nice for US Thanksgiving at the end of November - 4th Thursday to be precise!), and getting more reds and golds than the oranges of autumn.
I don't do a lot, but I start doing things like paper chains with DD from late November, and putting up a few things like a Santa spinner (cheap and tacky from the Euroshop - but she loves it!) hanging from the sloping ceiling on the way up to her room in the attic around 1st December. The advent calendar also goes up for 1st Dec - and that hangs in the kitchen (big fabric panel style), and a festive fleece blanket comes out for the sofa in the sitting room (DD is always curling up under rugs year round, and we have this for the Christmas season). I keep meaning to do an advent wreath with the 3 purple, 1 red and 1 white candle - and keep forgetting.
I change DD's sheets anytime from 1st onwards, whenever I get around to it, for the red sheets and festive duvet cover set. We only have 1 but I do try and wash that before Christmas again to have it fresh and lasting until the tree comes down (6th January - although DH wants it down earlier some years before we all go back to work/school).
The wreath goes on the door about the 2nd weekend. And a few snowglobes get positioned around the house. And I have a few Christmassy mugs and a plastic plate and glass for DD that come out at some stage too. And the crib - we have a tiny wooden one for the hall table usually as the big one takes up that whole table (so no place for the lamp, keys container or phone charger etc).
The tree goes up later in the month. Usually because it's a real tree and I don't want too much needle drop indoors.
The towels in the kitchen and handtowel in the bathroom are the last to change as I only have a couple of those and they get very well used. So I want those for Christmas itself. I also only take out the other festive crockery items for Christmas week (a couple of serving dishes, a tiny cream jug, and another couple of mugs).
Everything gets put away on the same day in early January. So its a gradual build-up but a massive clear-out and "sterilization" back to "normal" at the end.