I put ours up after 9 Lessons or Christmas Eve, whichever, and it goes down on 12th Night. It's so lovely to me to keep this tradition that I had as a child and pass it down myself. I stir up on the last Sunday before Advent. From Dec 1 we have mince pies and an advent calendar, then decorations up Dec 24 - Jan 5, all down by Epiphany, the 6th, except the lights, which we keep up until Candlemas, Feb 2.
We have a feast on 12th Night to eat up all the festive food and swap any unwanted presents and our tall friends are tapped to take down the high things. Then my brother makes short work of the trees with the chopsaw and I stack it for kindling. I like the rhythm of it, the same every year.