I have a number of Buff Orpingtons and Speckled Sussex roos that are going under the knife in the next while. HOw do you know when they are the right size? I have never butchered chickens before and am feeling my way around the whole deal? THey are 9 weeks old now but they don't seem big enough yet.... what happens if they are too young? Just less meat? (I only have 5 hens in that lot and there are 12 roos! I think...)