In what period was the schedule devised?
In which period did the calendar initially developed?
During what period did the agenda come into existence?
At what time did the timetable originally devised?
In which period did the agenda firstly envisioned?
At what time did the timetable firstly devised?
At what time did the schedule generation?
At what time did the schedule come about for the first time?
History of calendars Wikipedia
