Just to add I think you have made the right decision, your dog is far too young to be used as a stud if you want him to be a good worker, I've seen a few dogs now that once they have had their first mating start thinking more between their legs than between their ears, in that I mean they can stop listening to command, start scenting more and actively go for the bitches more, it would be a shame to ruin him before he is even fully trained.