Are they still tending to their chicks? They probably won't lay while they're mothering their broods. I find that my Mama hens want to stay with their chicks for about 6-10 weeks, it varies from hen to hen, and the voices only they can hear in their heads.
Most of my broodies are bantams who can fly over the fences of any pen. They are kept in a pen with their chicks and they all eat chick feed while they're in there. When they feel ready to leave the chicks they'll hop over into the layer pen, and it seems they start laying within a week after that.
If your hens are together with their chicks you should feed them all chick starter, it's better for the chicks and all right for the mama hens to eat while they're not laying. I'd rather have my chicks & mamas on chick starter than have everyone on layer crumbles.