Jusqu'à combien de semaines St. Stephen's Day / 2nd Day of Christmas?

St. Stephen's Day, or the Feast of Saint Stephen, is a Christian saint's day to commemorate Saint Stephen, the first Christian martyr or protomartyr, celebrated on 26 December in the Western Church and 27 December in the Eastern Church. Many Eastern Orthodox churches adhere to the Julian calendar and mark St. Stephen's Day on 27 December according to that calendar, which places it on 9 January of the Gregorian calendar used in secular contexts. See wikipedia for more details.