I actually buy the dog pads. And when first training I would lock him in your room with you at nights. And put them where you want him to go. I to prefer them going outside but the pads do make it nice at times when they can not wait. Better then going all over the house
I have heard people having them on a leash inside so they know what there up to all the time. Of course just while your training. That way they are never out of site. It just takes time if your consistent on whatever method you chose. You will get him trained