the twelve days of Christmas start on Christmas not before Christmas. thanks

the twelve days of Christmas start on Christmas not before Christmas. thanks
Or, “I have Thoughts about secular Advent and also want to clear up some other stuff while I’m at it”
I have an ambiguous relationship with Christianity but apparently I have enough of one (and I’m neuro-something enough) that I have Opinions About and need to explain the various times relating to Christmas. Standpoint disclosure: I grew up a mixture of Free Methodist and United Church of Christ (UCC). Also, whenever I talk about liturgical timing in this, I am referring to the ‘Western’ Christian church. Other places and denominations use other calendars and dates for (imo) cool/interesting reasons, but I don’t know enough about them to talk with any reliability.