Around this age is when I got my puppy the martingale collar and started using mild corrections to help deal with pulling. Eventually I had him walking perfectly with me for a whole 20 min walk. No pulling at all! Now I won't say he was in a perfect heel glued at my side and watching me the whole time, but he learned quickly not to pull out to the end of the leash anymore.
In combination with the occasional change of direction and/or stopping for a few seconds and taking a few steps backwards whenever he pulled, I would also give a light correction to help get his focus back on me. He had this look like "oh yeah, theres a human on the other end of the leash" lol! Then I'd use treats and praise if he loosened up on the leash and walked nice with me. I swear by the end of the week he had the idea and didn't pull on walks anymore, even at this young age.
By 6.5 months the martingale wasn't working anymore. Gary decided he didn't care about walking nice with it on anymore, so I had to upgrade to the prong
. Even though I didn't want to have to resort to it, I must say it is one of the most amazing tools I have ever used. I used to be a halti/gentle leader advocate, but now I am liking this tool better as the dog doesn't have to "get used" to wearing it. I still like the gentle leader and use it for my shepherdx! It is great if your dog doesn't mind having a strap over his nose.