In this year of overwhelmed shipping systems, there’s a pretty good argument for importing Epiphany into the more-or-less-secular version of Christmas. (Bear with me!)
The “Twelve Days of Christmas,” retail version, start on the first of December so you can have a bunch of one-day specials that get the non-last-minute (or in time for shipping) Christmas buyer. The countdown version starts tomorrow or the day after, a half-sized version of the 24-day countdown calendar.
And of course there’s the Bob & Doug McKenzie version.
But the actual answer to the question they pose is: the twelve days of Christmas are from December 25, Christ’s Mass, to January 6, the feast of Epiphany, or Little Christmas. I didn’t grow up in a “high church” tradition (or inherit any of the traditions of my Amish grandmother) so this wasn’t a thing for me, but I think it’s a pretty good 2020 idea.
Epiphany commemorates (among other things) the arrival of the Magi, the three Wise Men, so it’s a gift-giving thing. It’s also a traditional day of taking down Christmas decorations (unless you’re a leave-them-up-until-Candlemas type).
So here’s my modest proposal. Embrace the unavoidable: leave the tree up until the 6th, keep putting late-arriving gifts under it, and have yourself a merry Little Christmas.