I am not in favour of mixing holidays. One holiday at a time! You see in the Nightmare before Christmas how things can go wrong when you mix holidays.
As mentioned in the obscure holiday thread, in NL we have a holiday on the 5th of December with its own decorations, songs, movies. So in my house nothing Christmassy before the 6th.
(And I am not a Christmas person, so probably no decorations at all, but if I did, not before the 6th)