You already messed that dog up.

That dog needs to be out in the coop and not in the house.

I would start training it from the time it was 12 weeks old.


Ignorance gone to seed!! Wait until 12 weeks to start training? Get real.
He should have been being socialized from birth. The closer the bond with his master, the more he will try to please him. Just use a small amount of common sense and keep the lessons short and fun. If the pup knows you are training him, you should back off and make everything fun so that he doesn't realize he is being trained. When he is older and ready for serious training you will find that all the simple games that you played has set a pattern in the pup through the repeated repetitions.
You can't whip a dog and make it hunt. If the pup has the hunt in him, treating him decently will never ruin him as a hunting dog.