I don't translate kg into lbs, but my current puppy was absolutely huge at 11 weeks when I picked her up.
I'm confused that if both parents are GSDs how the breeder can also assert "timber wolf" in there? That might be wishful thinking on the breeder's part or just an offhand remark that's meaningless.
My pup heels when I have kibble in my left hand, and is just now at about 6 months interested in messing with "her" training toy. Engagement is something I've had to work on with her. My 4 yo, as a pup, was a complete contrast. She was smaller, came "out of the box" with full engagement, house trained easily, has not counter surfed then or now, played fetch or keep away with any toy from the get go.
So if the behavior is what you are questioning regarding either age or breed --- don't. It varies greatly from dog to dog. (within the breed.)