The video below is a great example of what you can expect from a puppy that has not been leashed trained at all. It usually only takes a week of 5 to 10 minute sessions per day before 8 week old puppies get used to walking on leash.
I would suggest using at least a 6 foot leash so your puppy has some room to make mistakes. Obviously you don't want to pull on the leash too much but you can give little corrections like a quick pull toward you if your pup gets off track or distracted by something and won't come to you. You just don't want them to feel like you are pulling them. It's ok if they try to back up and cause the leash to pull tight. Usually you can just give him a second and he will make a move towards you.
Your puppy is testing your leadership ability at this age so be firm and make good eye contact :)
