If you allow the dog to learn that the leash is an essential part of communication, it will need it in the future. Many people tug on a leash to get the dogs attention and then give a command. This physical cue will override any verbal cure you are attempting to use, and we'll become part of obedience for the dog.
Until much later in training (roughly 6 months), when the rules of leash pressure are shown to the dog, I don't use the leash for anything but management. If I need to get the dogs attention, I use my voice and movement to become more interesting than any distraction.
Engagement and focus on the handler are the first step in the training process, and until the pup is pushing and offering behaviors, I don't begin any formal training.
When a dog saves the life of a man, it becomes clear that partnership knows no bounds.
Fama - T.E.D.D. OEF XI-XII (GSD)(RET)
Marshall - T.E.D.D. OEF XII-XIII (Lab)(SF EDD)
Lucian - Med Alert / Mobility SD (Cane Corso)
Pud - the old man (Pit x Lab)