IMHO there is no way to be sure. They look young to me, I'd guess 6 to 8 weeks old. The cock bird should have start crowing at 5 or 6 weeks old. My last batch started laying 2 days before they were 6 weeks old. Changing pen mates and stress will make them hold off laying most of the time thou..... I dont know where you live, but here, coturnix are getting enough natural light hrs to lay. But they gotta be happy, comfortable and mostly stress free. Good luck, I hope your birds work out. Bill