Good job! Keep in mind he's been practicing his pulling for a lot of of years, so he's not going quit with just a few tries at anything. He pulls, you go - that's what he's used to. Now he pulls, you stand still. HUH?
Hmm.... Thinking must start going on now.
What must happen? Ok, so I must pull harder!!! Mom still doesn't move. I'll wait her out. (and sometimes, this waiting takes F O R E V E R ). Finally, they get antsy cuz there's stuff to sniff, places to go, etc - so if for no other reason, they finally turn around and look you in the eye. At this point, good job on your part, altho you don't even have to speak, say good boy, reward, etc - the act of moving is his reward. Honestly, if he pulls 2' after you start walking and you have to stop again, then do it and wait him out for the next eye contact. I know it sounds ridiculous, but give it time. Charlie is finally going to have that AH-HA moment when he realizes that whoa, mom is connected to the leash, we're a team and should be walking
together (as opposed to you feeling like you're being dragged by the lead dog in a sled team - I do get it, trust me!).
I know some people like their dogs walking perfectly next to them. Frankly, I don't care where mine walk (within the 6' of their leash) figuring it's their walk, and as I take in the world by looking at it, they do so thru their nose, so must "read" the bushes, grass, shrubs, etc as we go - and of course, leave peemail for the next passersby.
My boy walked just like yours (nothing like being pulled by an 80 lb freight train!), and every now and then, starts out that way (over excitement, I think). I loved that seminar, truly. It takes him no time at all to remember, hey, I'm not alone out here, there's two of us - and what a difference. Her method has been different than most any I've ever heard described or taught ... because of the eye contact. That's the one big difference. And honestlyl, I'd rather my dog choose to make a decision to do or not do something because they're including me in their decision every single time - than rather they just do or not do something cuz "mom said so". Give Charlie time, this is new, he's got to have time to realize all this, think about it, process it, let it settle, and get used to it. His 'not pulling' won't happen overnight. Take all your patience with you when you go out walking - and don't forget to have fun!