Spring hatched White Leghorns - 18 wks.
Spring hatched ISA Browns - 19 wks
Spring hatched Rhode Island Reds, Barred Rocks, New Hampshires, Buff Orpingtons - 20-22 wks
Spring hatched Easter Eggers (very mixed) - 20-22 wks
Summer and fall hatched birds of the same above may lay much later.