A chicken begins laying eggs somewhere around 4-6 months old. Ours are only 3 1/2 months old so it totally took us by surprise when we found an egg in the coop. The next day another egg and then yesterday we found two eggs! They're a bit on the small side which is to be expected at first.
We have 12 chickens and if they were all to lay an egg a day.... that's a lot of eggs!!:)