For the past five years I've had a Christmas tree in my urban garden. I've always decorated my Christmas tree with lights and have hung ornaments that are bird feeders filled with suet which I replenish on a frequent basis.
My standard has been to put up a Christmas tree anytime between December twelfth and December seventeenth, then leave it standing until mid February. This way the array of wild birds who visit my garden will have a place to keep warm during the coldest winter month as they nosh. The Christmas tree seen in the picture atop this entry is the one I had last year.