Some dogs develop later, some have one drop and not the other, ask your vet, he should have had them drop by now, genetically he may have a fault, which you don't want to put into the gene pool. Who ever asked you to breed him at this young of an age is not a responsible breeder...now if they would like to wait and see how he turns out at 2 yrs old, then okay. You need to see if he is breeding material if he's sound of mind and body, health certificate and hip certification. Temperment is part of it, and has he done anything, got any titles, even a CGC or your equivilent. If you care about the breed you have to then make sure you better the breed not breed just to make money or just because he's "cute" and you want one "just like him", dogs are not clones. I love these bully breeds, and don't like what people do with them, that's how they are getting a bad rep. IMHO