It’s a question that not many people know the correct answer to, so here it is. Generally speaking the answer is on or around St. Andrew’s Day which is the 30th November. A more definitive answer can be found in “Tables and Rules for the Moveable and Immovable Feasts” in the “Book of Common Prayer” for the Church of England.
Advent Sunday is the Sunday on which the Church commences the celebration of the pending birth of Jesus on Christmas Day. The “Rules to know when the Moveable feasts and Holy Days Begin” states that : – “Advent Sunday is always the nearest Sunday to the Feast of St. Andrew, whether before or after.” Advent Sunday could only fall on any day from and including 27 November to and including 3rd December.
A further table “Lessons Proper for Sundays” has a sub-heading “The Sundays of Advent” and under this it lists four Sundays. Thus the period of Advent consists of four Sundays.
The answer to the question
As Christmas is a Christian religious celebration the answer to the above question is “Advent Sunday” which we now know is the fourth Sunday before Christmas and will fall on any of the days from 27 November to 3 December.
If these assumptions are correct then this would be a world wide standard, not just Australia.
Taking Christmas lights down happens on The Feast of the Epiphany which is on 6 January, after the Twelve Days of Christmas. The Twelve Days of Christmas is the festive Christian season, beginning on Christmas Day (25 December), that celebrates the birth of Jesus Christ, as the Son of God. This period is also known as Christmastide. This is different from the Octave of Christmas, which is the liturgical time from Christmas Day until the Solemnity of Mary on 1 January. The Twelfth Day of Christmas falls on 5 or 6 January depending which tradition is followed. There is similar confusion about the date of Twelfth Night which is commonly held to be 5 January but some hold that it is 6 January. The Feast of the Epiphany is on 6 January which celebrates the visit of the Wise Men (Magi) and their bringing of gifts to the child Jesus. In some traditions, the feast of Epiphany and Twelfth Day overlap.
So there, you are now informed officially.
By the way, please do not use Xmas, as it is considered disrespectful by many Christians. The Cambridge Guide to Australian English Usage states that the spelling should be considered informal and restricted to contexts where concision is valued, such as headlines and greeting cards. The Christian Writer’s Manual of Style, while acknowledging the ancient and respectful use of “Xmas” in the past, states that the spelling should never be used in formal writing.