Most begin on December 1st regardless of when the Christian festival of Advent actually begins and usually takes the form of a ‘countdown’ to the 25th
As with this cake there are usually twenty-four “windows”, one of which is then opened, or in the case of this lovely example eaten, every day leading up to Christmas.
The origin of the Advent calendar comes down to us from the Lutherans who, at least as early as the beginning of the 19th century would count down the first 24 days of December physically. One simple means of counting the days would be a chalk mark on a wall or door while a rather more elaborate means would be the lighting of a candle and the singing of a different Christmas Carol on each day.
But, whatever you choose, I still believe that a symbolic cube of cake is as good a way of counting down as any other!