If you wait until December 12 to go buy a Christmas tree...
You'll find that there are no live trees left at the 3 places you went to.
You'll find that the only fake trees left cost $100 and look like toilet bowl brushes. You can buy the display tree of one of the nice fake trees but who wants a tree that everyone else has fondled?
You will buy a tiny tree just to have one.
Next year, we will go tree shopping a bit earlier.