We have a RIR and a mystery chick that were born around Aug 8, 2012. Neither of them are laying yet but by stereotype the RIR should start laying around next month I think. Is it too soon to start feeding them layer feed? I've seen other people mention in the forums to just supplement regular feed with oyster shells instead. I know that oyster shells are a calcium supplement but do they also count as grit? Any tips or advice would be greatly appreciated. Thanks!