Mine first started at 16 weeks they are now 19 week not all of them are laying now. I have got 4 eggs or more a day from the 12 of them for the last week.
I have 3 red sex links and 3 cinnamon queen hens. All are 21 weeks old and so far no eggs. Will let you know if I get an egg. Of course, I am certain the high heat we have here in Phoenix, AZ has something to do with the delays.