Now you do! :)
The Christmas liturgical season ends on the feast of the Baptism of Christ which is the Sunday after Epiphany (which for Catholics is the nearest Sunday to the sixth of January). The octave of Christmas (that's Christmas-Christmas*) begins on December 25 (Christmas-Christmas-Christmas* ;) ) and ends after seven more days, making it eight days in total (of course).
*We don't actually call it that. ;)