Take it down on 6 Jan - Feast of Epiphany, after the wise men have been and the twelve days of Christmas are complete.
We did this as kids because Dad was German. I have great memories of going out to get the tree on Christmas Eve, then having the dinner that night, then going to a midnight church service.
Christmas Day is very relaxed, though. No cooking.
DH doesn’t agree with this approach, and wants to put the tree up in November and leave it there until we’ll into January. Terrible.