D&D 5E (2014) When (Greyhawk Calendar) were the Temple of Elemental evil modules set?

[Sword of Spirit]

Does anyone know of an official date, or was it just whenever the DM feels like (not that that isn't the true answer anyway, but I'd like to know if they gave more than that)?

 

[Nagol]

579 Common Year is the base start of T1

569 Common Year is the first battle of Emridy Meadows according to the Greyhawk folio timeline and T1 happens a decade later.