Join Date: Nov 2013
Location: Lake Tahoe Area
At 8 months his growth plates are not close to being closed. You risk permanent damage to the joints if you add too much weight and work him too long. I would work him with just the vest on and no weight for quite some time. Focus more on agility and muscle development using his natural weight and athleticism. Don't blow it now and have injuries the rest of his life. I'll let others talk to when you could start adding weight.
What is it you want him to carry?
Dutch Shepherd - Ptygo (Tee-Go) de las Flores
Rescue GSD - Freyja (Husband's Dog)