Hello from California.
So I just got a 5 month GSD.
He's pretty awesome for the most part, took the change of families well, smart as a whip, gentle for the most part etc. Issue is that he is pretty fearful, I'd guess a case of under socialization, he lived in a quiet neighborhood with a yard, I live in the middle of San Diego with next to no yard.
Right now I've had Hondo for about four days, he's JUST starting to warm up and act like a puppy, so I'm giving him a couple weeks before I go looking for a trainer. I've had a pile of large working dogs, a German, Shilo and King Sherperds, Coroso, Rotti, etc. This is the first time I've had one that was skittish, so I'm in new territory. My concern is that he's 55 pounds or so now at barely 5 months, he's going to be big, he's still all ears and paws. I don't want a dog of this size acting out of fear.