100 years after the MMO is set.
This seriously pains me, it hurts just a little less than Warhammer Online.

Dude, dont quote the wiki for lore.
Or anything else really. Its a bit full of misunderstandings and things that are wrong.
The http://www.uesp.net/ has the best information on the games and the http://www.imperial-library.info/ is the place to go to for lore.
Fact is that we dont know a lot about the second era, nor about the time the MMO is set.
There is only one source for the founding of the first Aldmeri Dominion.
If some leeway is applied to both these dates, they match up pretty well.