Advent is not the time from December 1st until Christmas, it starts on whatever days the fourth Sunday before Christmas happens to fall on that year. This way, there are exactly four Sundays in advent.
If Christmas itself should fall on a Sunday one year, it doubles as the fourth Sunday of Advent, i.e., then the first of Advent will be only three weeks earlier.
In Eastern Christianity, the Nativity Fast starts on a fixed day: November 15.
(I never could wrap my head around all this. I had enough problems with Easter events, where the math makes a detour through a Lunar calendar.)
EDIT: And my memory of the Tradition is wrong too, it's supposed to be 24 - as confirmed by https://news.ycombinator.com/item?id=45710618, and corroborated the two "Paw Patrol" themed Advent Calendars I just found still stashed in my home office.
j/k ;-)
> (first day of spring)
It's actually the March equinox. "Spring" is true only in the northern hemisphere. What's more it's the ecclesiastical equinox, not the astronomical equinox, whose date actually varies depending on the year.
Never mind that all this is descriptive of dating in countries that grew up with Western Christianity. Countries where Eastern traditions dominate often date it differently.
All good will to you both = )
There is no time for actual advent or winter calmness in general.
We can only hope. The Christmas song containment fields are weakening as we speak.