My mother-in-law just emailed me about this! It actually began today (Nov.30) but of course I think you should just jump right in. The description does say 15 times a day. I’m guessing you can just say it hourly upon waking? Not sure, though.
Christmas Anticipation Prayer
Beginning on St. Andrew the Apostle’s feast day, November 30, the following beautiful prayer is traditionally recited fifteen times a day until Christmas. This is a very meditative prayer that helps us increase our awareness of the real focus of Christmas and helps us prepare ourselves spiritually for His coming.
Hail and blessed be the hour and moment
In which the Son of God was born
Of the most pure Virgin Mary,
at midnight,
in Bethlehem,
in the piercing cold.
In that hour vouchsafe, I beseech Thee, O my God,
to hear my prayer and grant my desires,
[here mention your request]
through the merits of Our Saviour Jesus Christ,
and of His blessed Mother. Amen.