I have (7) 8 week of chicks. Currently they are eating free choice medicated chick starter and water. They free range in our yard about a hour a day. These are our first chickens and I am trying to figure out what is the best nutrition plan. I have a few questions: 1) At what age should they switch to a layer feed? 2 If/when do they need to have grit added to their diet? 3) What other things (I have seen mention of oyster shells) should be included and when to include them? Thanks...you guys are the best!