There are some dates for some classes:
- Hunter/Sunspear (Pridelands), 8/31
- Frostmage (Glacial Peaks), 9/28
- Thief (Zaejin), 11/02
So it could be Shaman (Wild Plains) or Warpriest (Leonis Empire) (the 2 remaining well-known classes).
Note that there is 4-weeks gap between Hunter-Frostmage and 5 weeks between Frostmage-Thief… So these dates could be wrong .
And: