Our chickens started laying at all different ages. The earliest we have ever had a chicken lay was a Red Star who started laying between 16 and 18 weeks old (cannot quite remember which). Chicks out of the same hatch date took as long as 26 weeks. I hatched out my own chickens that were mixed breed - the earliest started at 20 weeks of age and she was consistent about 6 out of 7 days of the week except when she went broody of course. Right now her daughter is 23 weeks old and hasn't started laying yet - but she is grooming the nest boxes so it should be any day.