We observe the "traditional" Christmas season, not the "retail" Christmas season.
Tree and lights go up about December 12th, ad the beginning of the 12 Days of Christmas and come down after January 6th, the Epiphany.
My wife and I agree on this despite coming from different religious beliefs and upbringing. I grew up going to church every Sunday and that was my church's tradition. My mom had a different experience. Growing up, Santa brought the tree and all the gifts on Christmas Eve and they stayed up until the Epiphany, so for her, anything Christmas before Christmas Eve was early.
My wife's religious experience began with going to Kindergarten at a Catholic School, and ended shortly there after when the nuns asked her mom not bring her anymore! So she basically grew up with the "Retail" Christmas schedule which she finds ridiculously long.
As for shopping, I do most stuff online after December 15th. It's usually on sale, and on my front porch without expedited shipping in 3 or 4 days. Funny thing is, I have yet to try and buy something that wasn't still available.