I'd like to put it up on Christmas Eve and take it down at Epiphany (6 January), but DH is going to want it up earlier. It'll probably go up in mid-December, but will definitely not be up beyond Twelfth Night. I'm with ksand24 on this - it's bad luck to keep it up longer! Plus, to me, it makes it less special to leave it up so long. And we always have a real tree, so I don't want it up and drying out for too long.