I wanted to hatch out some of my own chicks from my layers this year. All the hens are heavy breeds: BO, Silver Laced Wayndotte, RIR, NHR, Barred Rock. My roo is a RIR banty X EE. How do I know when the cockerls would be ready to butcher? I talked to the processing plant and they said that in late summer I need to call about a month before hand.