we started using the bells right when we brought Buddha home at 8 weeks. We started out taking him out every 30-40 minutes, I would gently make him hit the bell with his nose and I'd say "go potty". We would carry him out with a leash to the dirt area we wanted him to use for his bathroom. Then put him down and say "go potty" and use the leash to keep him in the area and not run to the lawn.
If we didn't carry him he would just squat as soon as he got to the lawn.
Once he started knowing the dirt was the potty spot we started just fast walking him out to the spot on the leash. And then eventually we could just open the door and he would run right to the spot. If he had any lazy days and tried to test us, back on the leash for some refresher training. When it was done right we always went way overboard with the loving like he just won the lottery, sometimes getting a treat too.
He's now on total autopilot. The bell has worked out great, Except when my wife and I were both trying to get ready at the same time to leave one day and didn't hear the bell. Lets just say he was at the door as long as he could and then even tried to find us to tell us he had to go.........he didn't quite make it to us. I felt like such a bad parent right then LOL
So yea, I need to get a louder bell.
Also as an added bonus because of keeping him to dirt to do his duty, he will not go potty on lawns, when we visit family, I just take him to a dirt spot, say go potty, he goes potty and that becomes his potty spot while we are visiting, whether I take him or not.