I got my puppy at 10 weeks, used a collar until today at 14 weeks. I clicker train and he is very obidiant he walks beside me and very little to no pulling, I like the harness after todays first walk but I think I may have needed the leash in the beginning.
Clicker training was the best thing I did out the gate, tonight for example it was kennel time, he didn't want to go on his own. I grabbed the clicker, got a sit (treated) went to kennel pointed and said kennel and down the stairs he came and in the kennel. (treated) and goodnight
Also click and treated to heal and walk beside me randomly to promote walking as he wasn't to fond of it.