Merriam-Webster defines The Epiphany as:   "A Christian festival held on January 6 in honor of the coming of the three kings to the infant Jesus Christ."

The 12 Days of Christmas comes from Dec 25 (the birth of Jesus) to Jan 6 (the arrival of the Wise Men).  According the Matthew, the wise men came after the birth of Jesus.  So please celebrate The Epiphany with your fellow Christians!