what days and ages does each stage age up

Eggling stage lasts 3 days/ 72 hours (locked at 72 maturity hours until hatched, autohatch after 24h form first reaching 72h) (starts: 0h of Bred/ Bought, random if found while exploring)
Hatchling lasts 6d / 144 h (starts: 72h)
Adolescent lasts 18d / 432 h (starts: 216h)
Adulthood starts at 27d / 648 h

It takes roughly 72 hours (3 Days) for a newborn Eggling to become a Hatchling. It then takes roughly an additional 144 hours (6 Days) for a Hatchling to become an Adolescent. It then takes an additional 18 Days for an Adolescent to become an Adult.

(Copied off of the forums page)

*Hope this Helped*

thank you