We put ours up on Saturday and that felt early - house full of atheists - usually take it down on 6th January but sometimes earlier. I worked until 6pm on 23rd and was bone tired when I got home, I couldn't muster much interest in Christmas until we cracked open the Bailey's and wrapped the presents after dinner on that day.
My parents are religious and put theirs up earlier than us, and trees in their church.
Christmas trees aren't a Christian tradition though any more than fairy lights are! I don't think religiosity and how early/ late a person decorates are directly connected.