We don't even get ours until the 13-16th. That was it's still nice for Christmas. I've never actually heard of a specific "ut-up by" date when it comes to christmas trees, but I suppose everyone has their own personal preference.
Well, it's the tradition in my family to put up the tree the day after Thanksgiving. That way we have the pick of the finest trees before they are taken.
My family put up the tree the 22/23 of December. We pick it about a week before, which means this year, I am not going to be able to help pick the tree. Stupid education and wanting to live alone!
I heard that is bad luck to have your christmas tree up too long after xmas is over, so putting it up in July like _________ said could be a bad thing.