There are several advantages to this; not the least of which is that unlike the mad rush of opening of the gifts on Christmas Morning, you get to set your own holiday parameters – the celebrating starts with the first chocolate popped into your mouth, and only ends when the last cookie is gone.
Here is my list of what makes Christmas, well, Christmassy:
cookies! especially shortbread and gingerbread
egg nog (with spiced rum, of course!)
turkey with all the trimmings