My dog is a GSD and I got him at 8 weeks. We did several months of schutzhund training.
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@Sweets , I made him wait to eat, he hat to watch me (not the food) until I gave him the ok to eat. We had to work up to it.
I crated him when I was at work for about 2 months until he was old enough not to chew on the couch and wires. My wife would come home to give him a bathroom break.
After that, he was old enough to let hang out at home alone. I have a doggie door, so he can go to the bathroom whenever he wants.
As far as a leash, I live in a very populated neighborhood, so we had to work our way to off leash privileges. I would teach him the boundaries of th he yard by recalling him if he went too far. When I sat on television front porch, I'd have him leashed for about a year untill he stopped reacting to people walking by, kids on bikes, people walking dogs... etc. Now he doesn't need to be on leash, as long as he doesn't see a cat or squirrel.
Just take your time with him. Don't lose your patience and always have him around you and people. Before long, you'll be reading each other's minds.