When did the schedule devised?
In what period was the timetable first introduced?
In which period was the timetable emerge?
In which period was the calendar firstly invented?
During what period did the calendar originally thought up?
In what period did the schedule initially established?
During what period was the timetable inception?
In which period was
the schedule emerge for the first time?
The History Of Advent Calendars The Fact Site