As I shell I separate the ones that I feel are a bit over ripe. To me the texture is a bit gritty compared to the younger ones. To be honest I never know when to pick. I can feel. I can see how big the pod is. But none of that really tells me. I won't know until the pod is opened. Beans that hold on to their attachment to the pod are still young enough for me. The others I put into a different jar. I'll still eat them, but in a different way.