You shouldn't put them on layer pellets or mash until they actually start laying. The difference between layer and regular feed is layer had more calcium, that's about it. It doesn't magically make a pullet lay. layer feed only provides the extra calcium needed for strong thick shelled eggs. Too much calcium in a chick or pullets diet before laying will damage their little kidneys. Early death, short life. Once a bird starts laying they may or may not need extra calcium depending on diet, if foraging they may not need any special laying feed to make the shells super strong. Once they start laying, and you give them layer feed, it only takes about a week or less for the shells to get super strong. You waited all this time for them to start laying, you can wait a week for super thick strong shelled eggs. I don't know about you, but I'm not in that big a hurry, if it means a healthier bird.
If it says "layer" on the bag, it is lower protein than chick feed or starter, and It Has Extra Calcium. I (or the co-op guy) accidentally killed about 50 birds @12 weeks old by feeding them laying mash/crumbles. Within two months they were dropping dead left and right, Kidney failure according to the Vet. And I had failed to double check the label on the bags of feed. Only after talking to the vet and him saying it was calcium poisoning did I go turn the empty bags over to find out it wasn't starter crumbles. It was heart breaking to know I had poisoned the little rascals.
