New Delhi, November 29 (ANI): Churches all across the Christian World start changing their drapes to violet or blue as the four-week-long celebration, which commenced this year on November 27, begins. Advent begins on the closest Sunday to St. Andrew's Feast Day, which takes place on November 30. This year, Advent started on November 27. It would last for the coming four Sundays. The festivities may last between 21 to 28 days depending on the date of the inaugural Sunday.