MUNDANE MYSTERIES: When does the 12 Days of Christmas actually start?

I wonder this every time I hear the song. When are we supposed to start the “12 days” in the “The 12 Days of Christmas”?

I always thought it was before or sometime in early December. Nope. It is actually about the 12 days AFTER Christmas, not before. The last day always ends on January 6th, which is a holiday called the Feast of the Epiphany.

Crazy!