DD always has to help - DH will if he is in the country (he travels a lot and I don't always want to wait on his return as that can be late enough in December).
If we are staying at home over Christmas, we get a real one. If we are travelling to our parents' houses (only 15 miles apart, but 250 away from us) we put up the fake we bought for our very first Christmas in our new house (6 weeks before our wedding, and only DH was living there yet). It is still going strong when needed despite being a Primark cheapie!
Sometimes we have a couple of things up before then, always DD's advent calendar, but sometimes a Santa twirler over the stairs and the paper chains that DD has made. The books and DVDs come out of storage on 1st December for DD. And I allow some of the crockery (a mug each, DD's plastic tumbler and plate) out too. But mostly it all comes out together. (The rest of the crockery, and the few little towels I have, I keep until Christmas week itself, and our original version of "Twas the Night Before Christmas" is saved for Christmas Eve).
We also buy a new ornament (or 3!) every year - often on our holidays or other travels during the year, sometimes coming up to Christmas itself if we see something special. This year, we have a log cabin ornament to build (from summer hols in Canada), a glass bear from M&S (reminiscent of Canada) and a garish clown head (impulse purchase on a recent work trip to Greece).
I play some of my Christmas CDs while we decorate, or else we turn on either Merry Christmas Radio (on Live365 internet radio) - or maybe even a Spotify list this year. But no tv as the tree is a SERIOUS business!!
We start the season with our first mince pies watching the Late Late Toy Show (which was last Friday night!!). Advent Calendar on 1st. Tree some weekend in middle of December, but usually up before school finishes. Final flourishes out on Christmas Eve. And everything goes away on 6th January (or maybe the Sunday before if it's early in the week like this year).
One thing I like to do once the tree is actually up is to take some reflection time for myself one night. When DH is out (he has a few "stag" events in the run up), and I've packed DD up to bed, I turn off all the lights in the front room except tree lights, have a couple of candles (and the stove!) lit, and maybe the oil burner going with a festive mix. Make myself a nice drink (I started with Jack Daniels when I was 16 back home, and it's been all sorts over the years, now likely to be a HM limoncello or sloe gin, or a nice drop of cognac - many's the year it's been something soft though too). And then lie on the floor under the tree, contemplating the year that has gone, where things are now (in all sorts of ways) and where I'd like them to get to, remembering times past, and just taking a chance for me to reflect and remember and plan. Maybe 15-30 minutes. Then getting up off the floor, turning on lights, and going back to the washing up, sweeping floors, checking lunches are made, doing more wrapping or card writing, trying to finish the knitting/sewing/mad craft idea for a present.......real life again!!