When I started any of mine on the prong it was properly fitted and I used the dead ring, not the live ring. That should be enough. No flexi leads if you are using one.
Robert has a good description of loose leash walking. Another one for me was to lock the lead in place on my body and not yank on the lead (for loose leash walking) but move my body and let the dog correct itself and learn to move on a loose lead relative to me. I would not go longer than a six foot lead, personally (leather or biothane)
NAPWDA Certified Cadaver Dog
Waiting at the Bridge (italics
=GSDs) (hemangiosarcoma=blue):Grim , Cyra, Toby
, Rainbow, Linus, Oscar
, Arlo & Waggles