The Twelve Days of Christmas have gone astray* in the commercial worlds of Britain and the US, in my experience. This year, my inbox received advertising for various 12 days of Christmas deals - all of which were before Christmas had even happened.
Historically, the days of Christmas start from the day after Christmas, which makes Epiphany, January 6th, the twelfth day. That's also why that was the day on which we took down our Christmas tree. (And it always feels odd to me to hear people apologize for not having taken it down by New Year's, even if they did buy it, say, weeks early and it's all but fire tinder now.)
This is also why, in Italy, the after-Christmas sales don't start until Epiphany. Christmas isn't properly over until then! Downside: a visiting Venetian friend who now lives in the US couldn't take advantage of the sales - her academic schedule required her to leave before today.
On Epiphany in Italy, the Befana comes to visit children and fill their stockings with candy. (Charmingly, she's an old woman who tried to go to Bethlehem along with the Wise Men, but got lost along the way. So instead she gives gifts to all other children instead.)
Venice in particular celebrates this with a regatta in costume. Today's weather was gorgeously clear, with vivid blue skies. A dozen or so boats rowed by men and women costumed as if Befane rowed down the Grand Canal, finishing past the giant stocking hung from the Rialto bridge.
This photo was taken a good half-hour after the race, with one Befana, along with three rowers who clearly weren't in the race, heading back from when the race had been rowed.
* Religiously astray doesn't matter to me in this case. *Calendrically* astray does.