I would definitely start working on walking manners now. The SPCA offers a puppy course for a very reasonable fee. If you don't have one near you, try walking short distances in your house or driveway. The leash should form the letter J . Reward with a high value treat ( penny size slices of hot dog or cheese) when he doesn't pull, or lag behind. Let him smell occasionally. Make it a fun activity. Don't scold or yank the leash if he is pulling or lagging behind, just stop walking and when you have his attention, then say something like "with me" and start walking again.
Repeat until you can reward him with a tidbit of treat. Praise to the skies when he goes four or five feet correctly. Continue in this manner. When he is doing well walking, have a friend or family member come so that he gets used to other people around, once he is used to people, include another dog. One distraction at a time and gradually add others to build on it. Good luck!