I'm a first-timer. My chickens will be 18 weeks old in a few days. No eggs yet, but I hear they could start any time now. I have maybe a little less than a weeks worth of "grower" feed left, and I have an unopened bag of "layer" feed. Do I need to buy more "grower" feed to give them until they actually lay eggs? The package says to feed the grower feed until 18 weeks or onset of laying. Would it be okay to start feeding them the "layer" feed next week even if they aren't laying yet? I have 3 Welsummers, 4 Dominiques, 1 Delaware, and 3 roosters.