Lore Timeline?

[Iscah]

Then again we can also go devil's advocate to argue that we've got no idea how elezen age and/or he could be a late bloomer.

We do know that actually, from the lorebook - they're slow to hit puberty (as their whole lifespan is 10-20% longer than average) and overtake Hyuran height around age 20.

That doesn't explain the "always five years since the Calamity" thing, or twenty since the fall of Ala Mhigo whether you're in ARR or Stormblood.