One of the paradoxes of the modern Christmas is that we spend a terrific amount on the celebration before the feast and then terminate it abruptly just as it should be going strong. So, the festive season starts sometime in late November, and culminates on Christmas Day, with another effort at festivity on New Year's Eve. But it shouldn't be so, and it wasn't always so.
By way of proof, take the Bach Christmas Oratorio, which is designed to be sung over the course of the Twelve Days of Christmas, starting on the first day of Christmas.
