Eorl's Grand Unified Timeline (as Calculated by Abner)

Using a wildly inaccurate graphical representation to aid the foggy recollection of the lost god Kodmelos, Abner calculated the following timeline:

   Time between creation of the world and Kodmelos's summoning: ???? years
   Time at which Ikulu dates the construction of the One-Year Dungeon: 250,000,000 years ago
   Time between Kodmelos’s summoning and the first flood: 5,500,000 years (Era of Haughty Scorpions)
   Time between first and second floods: 23,800,000 years (Era of Thunder Lizards)
   Time between second flood and “Noah’s flood”: about 520 years (Era of Adam)
   Time between “Noah’s flood” and the “Babel incident”: about 520 years 
   Time between the “Babel incident” and the Present Day: ~3300 years

Gershom figures that the Tower of Babel fell around ~2300 B.C., but Nicephorous claims that the bible left some people out of its genealogies, citing Luke 3 as an example, and thinks this is too recent.

If Nicephorous is correct, these numbers should be somewhat larger.

But even if he isn't...

The world was not created once, but many times, with many floods. This has probably been happening for all of time.

Noah: Indeed, the Introduction to the Lesser Homerica by Aeulius Nicon of Pergamon suggests as much, and it is quite possible that the gods of the gods (or even their gods), were we able to ever speak with them, may have forgotten how it began. Fortunately, our object is not to discover the origin of the world, but to prevent its destruction. Thus we are primarily concerned with the time from around the end of the Golden Age (when Kore fell) to the present day. So, you know, only about 30 million years plus or minus.