I'm a first time chicken owner and I have five 18 week old chickens and the feed store had me buy a 50lb bag of medicated Start and Grow. They said once I see an egg, I will need to switch to layer feed. She also said 2 of my chickens will probably lay eggs first (leghorns) and the others won't lay till later (a barred Plymouth rock and 2 amerucanca.) I've been reading you can switch now to layer and it doesn't matter and than I see don't switch till you see eggs. Help! What do you do? I also have oyster shell handy. Do I put that out in a separate bowl for when they start laying? If they start laying while eating the medicated start and grow can you eat the eggs? Last question, if only a few start laying first will they all be ok eating layer feed? Do you have to mix the feeds together till everyone is on the same page?