I had the same question last year, so I actually went shopping on Dec 31 and it was still at 50%. I went back the following day, Jan 1, and it was then 75% off.
My Target still had tons of stuff when I shopped last Jan 1 (I got there EARLY)...lighted reindeer, lights, tons of wrapping paper, ornaments, etc.
They didn't have a bunch of Christmas trees left, so I would suggest maybe getting those at 50% off for the best selection.
GOOD LUCK!