In creating my characters, I actually went through this Squenix Forum entry regarding lore.
According to this, the last year of the Sixth Astral Era was the year 1572, as that was the year that major events in 1.0 took place (i.e. reinstating the three grand companies).
I would assume that the year after that or thereabouts is when Dalamud descended upon Mor Dhona, thus beginning the Seventh Umbral Era and the year reset to 0. (Or 1... This was where I was confused as to what to make my characters' year of birth.) I believe I also read somewhere that Urianger spoke about a new Umbral Era beginning back in 1.0... I'll have to go find the thing I was reading.
1557 was when Ala Mhigo was taken over by the Garland Empire. 40 years may be too much. I believe the others were correct in saying 20 (21?) years.
According to this, the last year of the Sixth Astral Era was the year 1572, as that was the year that major events in 1.0 took place (i.e. reinstating the three grand companies).
I would assume that the year after that or thereabouts is when Dalamud descended upon Mor Dhona, thus beginning the Seventh Umbral Era and the year reset to 0. (Or 1... This was where I was confused as to what to make my characters' year of birth.) I believe I also read somewhere that Urianger spoke about a new Umbral Era beginning back in 1.0... I'll have to go find the thing I was reading.
1557 was when Ala Mhigo was taken over by the Garland Empire. 40 years may be too much. I believe the others were correct in saying 20 (21?) years.