STRINGS.CODEX.CRITTERSTATUS.FERTILITY.INCUBATION.CONTAINER1
A critter's incubation time is one-fifth of their total lifetime: for example, if a critter's maximum age is 100 cycles, its egg will take 20 cycles to hatch.
Incubation rates can be accelerated through tender intervention by a Critter Rancher. Lullabied eggs—that is, those that have been sung to—will incubate faster and hatch sooner than eggs that have not received such tender care. Being cuddled by a Cuddle Pip also accelerates the rate of incubation.
Eggs can be cuddled anywhere, but can only be lullabied when placed inside an Incubator. The effects of lullabies and cuddles are cumulative.