I've seen discussions about when it is that the Christmas season officially starts and ends, and for the Scalzi household, it starts after dessert on Thanksgiving, and ends on Epiphany (which is Jan 6), although as a practical matter it ends whenever Krissy decides it's time to put away decorations, so, usually that means Jan 2nd or so.
@scalzi In Australia I've heard of thing called the ‘Australian drinking season’. It begins at lunchtime on the first Tuesday of November when many business throw a party to celebrate a horse race in Melbourne and it lasts until Australia day on the 26th of Jan.