Would you stop still each time they pull and then walk again when they stop?
Yes, we did the stop and wait for there to be no tension on the lead before we moved. For me it really helped having a harness at this point as I just stood and waited it out, with a collar the sounds of her choking herself, whilst trying to swim with her paws to get the forward movement, were so hideous it was hard to just stop still.
My older one was probably closer to 2 before she walked nicely in most places, but it was a very gradual thing getting there. So she walked nicely at night, on our pavement walks where she knew she didn't go off lead at all from about 9 months. But walking nicely in the woods on lead where she'd normally be off lead came much later. As did things like walking down to the beach.
I'm lucky enough to have plenty of off lead areas, so we concentrated on recall but then always practiced some nice lead walking at the end when she was a bit tired.
But it did really seem like we had to wait for her to mature, because younger it wasn't that she didn't know what she was meant to do, but that excitement just completely took over.