At what time did the calendar devised?
In what period did the timetable initially developed?
At what time was the timetable
arise?
During what period did the agenda initially invented?
During what period was the schedule firstly conceived?
In which period did the calendar firstly introduced?
At what time did the schedule generation?
During what period did the timetable emerge for the first time?
Exploring the history and evolution of Advent calendars NPR
