Do you have fake eggs or golfballs in the nest boxes? This helps them figure out where to lay when they do start. I have 6 pullets, all 5 months old, and only 4 are laying. My Production RIR's I think are laying "fart" eggs while on the roost, every other day or so I get one soft shell egg under where they each perch. They are bottom of the pecking order so they are a little stressed. I honestly thought they would be my first layers, got that one wrong. Be patient and look for a possible hidden nest.
