I am no expert but I know with our we only have one that started laying and she is 8.5 months. The others we are still waiting on. We figure it just depends on the bird. They all grow differently and when we start to get eggs we start to get them. We chose to not rush things so the chickens will develop body and bone structure properly. Our birds do free range during the day light hours and eat lots of bugs, grass, vegetation, and the grower feed we give them.