What to feed at what age...
Chicks -> Growouts -> Chickens
Starter Feed - For the first 6 weeks your chicks should be on organic starter feed. Laying chicks require a 20% protein feed.
Grower Feed - Starting with week seven transition your laying chicks to organic poultry grower. You want the protein level to be about 18%. If you have any leftover starter feed go ahead and mix it with the grower for the first week or two.
Layer Feed - At about 15 weeks switch your chickens to layer feed. The protein level of this feed should be around 17%. If you have any leftover grower feed, mix it with the layer feed for the first week or two.