The Reform celebrates the transition from November to December with the feast of St. Andrew on November 30th (which honors the first disciple of Jesus) and Advent/Annunciation on December 1st.
This differs significantly from other Christian traditions, which celebrate Advent four Sundays before Christmas, and celebrate the Annunciation (the day on which Mary was told by the Angel Gabriel that she would conceive Jesus) on 25 March, a materialist nine months of gestation prior to Christmas.
For the Reform, the historical placement of the Annunciation is not as important as the inspirational role it plays as part of the Nativity story, so we celebrate it with Advent. And, by observing this herald of the Nativity together on the first day of the last month, AUR brings the entire narrative of the birth of Jesus together in one ritual season, setting aside December as a month of preparing for new beginnings: the beginning of the life of Christ, the beginning of the age of the Tree of Life, and the beginning of the new year when December finally turns over to January.
As the traditional feast day of St. Eligius, patron of goldsmiths, this day also begins the Twelve Days of Gold celebrating Mary as the Mother of Jesus, which ends with the feast day of Our Lady of Guadalupe.