One of ours started at 24.5 weeks. The other four haven't done a darn thing yet and they're now 26 weeks. Varies depending on breed, time of year, general health, environment, and individual chicken. Supposedly, you won't see anything before 17-18 weeks, and even then usually only with production-oriented birds.
Thanks for the input, I think I should ask my buddy if he is ready to start putting eggs in his incubator, I have 7 Rhode island reds and 1 leg horn he hatched last spring and they are laying very good and some big eggs, I hope he is ready.