We always keep our Advent Celebrations and our Christmas Celebrations separate - though they are related, they are two different seasons of the Church's cycle.
So we mark Advent by saying our prayers around the Advent Wreath, singing O Come O Come Emmanuel and having a reading as we add another character to our Jesse Tree. We will also say the wonderful collect Arise in thy strength we beseech thee O Lord and come; from the dangers which threaten us because of our sins, be thy presence our sure defence, be thy deliverance our safety for ever more; and we'll sing the Alma Redemptoris Mater.
This is the pattern until Christmas Eve (the collect changes each week, of course: we use the Sunday collect from the Extraordinary Form of the Mass). Only then will we start to decorate the house, put up the tree and so forth.
Which means I've been out in the rain collecting holly for the wreath, up in the attic looking for the advent calendars, Jesse Tree book etc, and singing the Alma Redemptoris to myself throughout the day.