Today is the fourth Sunday before Christmas, which makes today the first day of Advent. And 27th November is also the earliest possible date that Advent can begin, which is a consequence of Christmas Day falling on a Sunday this year. All of which begs the question, why doesn't your Advent Calendar start today?
Incorrect Advent Calendar start dates: 1st October: I can only assume that supermarkets start selling Advent Calendars in September because you're meant to start opening them and guzzling the nasty mass-produced milk chocolate on 1st October, not 1st December. (8 weeks early) 1st November: Ditto, for calendars sold in October. Maybe it's just as well there are no out-of-date nativity references behind any the windows any more, just milk-solid cartoon characters. (4 weeks early) 1st December: 1st December is the first day of Advent in only one year out of every seven (i.e. when Christmas falls on a Wednesday). However, manufactured Advent Calendars conveniently ignore this technicality and always kick off on the 1st, no matter what. All of which means, on average, you're getting less chocolate than you ought to be. (4 days late - 2 days early)
Incorrect Advent Calendar finish dates: 25th December: Lovely though it is on Christmas morning to open the final mega-window on your Advent Calendar and unwrap a huge great slab of chocolate, Advent actually finishes the day before. Plus, to be honest, there's quite enough calories to be enjoyed/endured on the 25th without adding even more. (1 day late) 31st December: A surprising number of Advent Calendars dribble on to a second post-yule climax. Has a countdown to the New Year become more important than Christmas, or is this just an excuse to boost sales by offering 25% more chocolate? (1 week late) 1st January: Advent finishes on the day before Christmas, not a week afterwards. Honestly, do calendar manufacturers know nothing about religion? (8 days late)