i have one laying that started about 21 weeks and one i dont think is as close. the one laying has much redder comb and waddles. I have an EE that started laying around 17 or 18 weeks and never missed a day. And one that started at 20 weeks.
I have 8 RIR pullets and 1 of them laid an the egg when they were 20 weeks. Did not get more than one a day some days none for about the next 10 days then there would be 1 or 2 then 2 or 3. Now we have gotten 6 a day for the last 3 days. They are now I think 24 weeks.