We ate a nearly two year old cock recently and he was lovely! I slow cooked him coq au vin but I think he might have been OK anyway. He was certainly like no chicken I have ever eaten before - much denser meat, far gamier, bigger legs, smaller breast - but in a really good way. So your cockerel should be fine whatever you do to him.
Not sure about the girls - I'm guessing they'll be quite a lot older.