If you've ever wondered how and why there are so many "national" days, I can't answer that. But I can tell you that National Advent Calendar Day was created by Aldi. It's Wednesday, November 3rd this year. It, also, happens to be the day that all 26 of their advent calendars for 2021 are released!
I think they don't necessarily get the point of an advent calendar judging by the one I really want "A Sparkling Wine Countdown to New Year." (It's not supposed to go to New Year).
There is, also, the 12 days of Bath Fizzies.
Anyway, this year, there are advent calendars for beer, wine, chocolate, cheese and coffee lovers. There are calendars for kids featuring Paw Patrol, Mattel and Legos. The holidays are coming!