I have 5 pullets that will turn 23 weeks old in a few days. Only one (a RIR) is laying yet, and she only started a week ago, after looking "ready" for WEEKS. Two of the others, a Delaware and a Speckled Sussex, look very close. The other two, an Easter Egger and a Salmon Faverolles, still have some obvious maturing to do, but I expected that based on their breeds. Normally, my spring pullets start laying a bit earlier than this; I don't know if part of the reason might be the extreme heat we've suffered all summer here (and are still dealing with).