I used a Starter-Grower/Start and Grow, 18% Protein till point of lay, 16 weeks for my Golden Comets. Some Grower/finisher is only 15% Protein.
To low for laying types of chickens, in my opinion. I think 18/20% is ideal from day old chicks up to point of lay and throughout Adulthood. I feed my 23 months old hens a 18% layers pellet. GC
I feed Starter/Grower 20% protein from day one and never change, but I do offer oyster shell in a separate container when they start laying. Quite a few people on here never feed layer feed at all, it's not needed for them to lay. The difference is lower protein and higher calcium in layer. There is no set rule, it's just easier if you have a mixed age flock, because chicks should not eat layer.