BE PATIENT, particularly with your cockerels. I can normally pick my keeper pullets by around 6 months, but my cockerels are 10+ months before I can make a final determination as to "stay" or "go". I have 1 cockerel right now (at 6 months old) that standing next to his sire is about the same size/stature, BUT, weighs less by almost 2.5 lbs. He is by far the largest of all my cockerels and will definitely stay unless he develops an odd DQ all of the sudden, but I fully expect some of his brothers/half-brothers to come close to the same size by 10-12 months old....several of them right now are just long and lean. Not certain about SPRs (perhaps Wynette can help with them specifically), but full tails on my males haven't finished until nearly 10 months of age