Cute puppy! The best thing at this age is to give him lots of good things to chew on! Some people suggest giving them gelatin. Many purebred GSD's ears don't stand up dependable until much later when they're done teething though, so I suggest you not stress about it and let nature take its course. I don't see much about this puppy that looks lab-like (are you sure of the mix?), but my first dog was a lab shepherd cross and his ears stood...give it time!
It's not the size of the dog in the fight, it's the size of the fight in the dog. Mark Twain