What about my young chickens that are still on grower. They still have a month before they start laying. What would be a substitute for them?
Whatever you can feed them. Grains, veggies, scraps, protein, bird seed. Our chickens go as nuts over leftover tempeh (fermented soy cake) as much as leftover meat scraps. There are different opinions about this, but you
could feed them layer feed (if that's what you had) if you knew for
sure they would start laying in a month. Often chickens don't start laying according to "the schedule" and don't start laying for 30 or more weeks. Since the days are getting longer though, they'll probably be laying sooner rather than later.
Some people ONLY feed layer feed, whether the chickens are laying or not (including roosters) and some people NEVER feed layer. The problem with layer feed is chickens can't choose their calcium needs and non-laying birds (molters, young ones, roosters, old hens, etc.) can get overdosed on calcium, which over an extended period can lead to visceral gout and kidney failure. No symptoms, they just die.
Since you have both layers and young chickens, you could make it easier on yourself and never buy two feeds again. Or at least give it a trial run. Feed grower to everyone (except chicks under 8 weeks of age, they need starter) and leave crushed oyster shells (best) or crushed egg shells (good) in a separate dish on the side. Any bird who is laying or is getting ready to lay will eat the shells (for calcium) and any bird who doesn't need extra calcium won't each much of the crushed shells. They're very good at knowing when they need more calcium.
This makes life so much easier if you have only one or two coops and a mixed flock of chicks, molters, current layers, broodies and roosters. Everyone gets a healthy meal without excessive calcium. If you plan to much of your flock every 9-12 months, perhaps I wouldn't worry about the grower+shells method if feeding layer feed is easier for you. The only real hard rule is to not feed layer feed to chicks younger than 18 weeks.