15wks , it saids it's all... Need to set a daily schedule and be consistent in applying it for the pup every day. Down to the nitty gritty detail. The schedule should be everything about who you are, how you want the pup to respect living in your house, so its natural to you when applying it the same every day. During that time you work on all you intro's into Learning and apply OB skills. Look at me when I am talking to you (get that calm eye to eye focus) This is our morning routine, This is how it is when I wake up first thing in the morning, How it is when the household is getting ready to go to work, what the pup will do , be during the day if you are away from the house. what it's like when we come home, how we spend our morning, evening activity time both structural and free play, potty time, meal times, how we spend rest time .. What you can and can not do in the house, what is your area for now in the house.
I know GSD's love the technical mechanics of routines. For me they thrive on it. Pick it up quickly and anticipate doing it on their own. All the while yall are being exposed to building team skills together, physical and verbal. Puppies are looking to you on how do we do things. Written out in a post it seems like a lot, but you do it every day anyway just living your life. GSD's love to be an active part with you. include them, there is nothing too small of a job for them, for their presence to be acknowledge with you. Even if that is only learning to lay down on their rug in the kitchen near you while your making breakfast... Especially if you have some extra eggs put to the side for when your done eating to put in their bowl for mastering the task of laying on that rug helping you in the kitchen. it's the little tiny moments of being a part of what your doing that they love.
The biting part is (do you really have to touch your puppy) do you really have to touch a GSD puppy at all to interact to train with them? I personally can say no you don't. When I got my Major he was 7wks .I picked him out of the litter at 4wks old and was planing to pick him up after 8wks old. What ever happen to him in that household, he was crazy when they called me to please come get him as he was tearing to shreds the adults, the kids and the other puppies ups . That I needed to come get him now. He was a true land shark by then, over excited, hyper, and biting to intentionally hurt , draw blood, to provoke a reaction from doing it. Puppies learn fast what works to get what they need. And Major had learned he didn't want to be touched for what his first experience in being touched had taught him. No intended abuse from those kids, but rough housing and loving the fact that Major went back at them harder and harder just fueled the kids that it was fun, until Major wanted to rough house attack and win all the time he got better and stronger at it and it was Major that didn't want to stop then, .................................................... and it was no longer funny to those kids or anyone else ....
If a pup is like this, don't rough house, don't play and get them excited ,they can't handle it, they need to learn to be calm follow a daily routine for the basics, have quiet time, and a calm household. you can teach all OB skills without touching. that's where you start with them. That is how you bridge the gab of what they do that you don't want and what you want them to learn instead to replace it. And be consistent ...