I'm working on training my three month old pup to not pull on a lead and my progress is slow. I didn't do a good job with consistency during my first couple of weeks of lead training so I understand that it is going to take some time to correct my mistakes and get the dog to understand what I really want. However, I was discussing this with another dog owner and he suggested that I get a choke chain to help things along. I'm thinking my pup is really too young to use one on him at this point but I'm curious about when all of you feel a dog is old enough to be walked on a choker?
By the way I am currently following some advice I received here about giving him a light jerk whenever he pulls ahead and telling him no and then telling him good dog when he is walking calmly at my side. When he gets distracted by something then I'm telling him to come without changing my pace and not giving him a correction. I figure at his age it would be a little bit much to expect him to not get distracted but it is perfectly reasonable to insist that he not try to pull me. So far I'm already seeing results. He is pulling far less than he was just a few days ago but we're still a long way from being where I would like for us to be.
One more thing while I'm posting

I've been periodically saying whoa as I stop moving when we're out walking together. I'll repeated whoa while I'm standing there and then telling him to come when I'm ready to carry on. I'm not giving corrections but I am giving praise when he does it correctly. At this point he seems to be learning the word well and will stop moving when I say whoa and stays relatively still until I give the release command. He's far from doing it perfectly every time but he's making progress. My question is, will this whoa introduction making formal whoa training easier or more difficult down the road? Also, he will sit about 10% of the time when he is on a whoa and I just ignore it - is that a problem given how young the dog is?
Thanks for all the help!