Shepherds don't fully develop their protective drives until they're at least 2 yrs old (I believe that's the correct age? I know they must be fully matured). Even then, not every shepherd has the proper temperament to be a "guard dog" or a "protection dog."
You can start visiting local SchH clubs, or start talking to a protection dog trainer now, though. If you're lucky one will be willing to do a "courage test" to see if your pup will grow up to have the necessary temperament to be trained for protection. This training can start early (not sure how early exactly... Another member will likely know the answer). But the puppy won't really have any way or training to actually protect you.
You CAN teach your pup to bark on command. My female has 2 different "speak" commands. My male is learning them (he's eight weeks as well). For a higher-pitched, normal bark I say "speak." Simple. If I, for any reason, feel the need to get her to use a more intimidating bark with a protective tone I say "protect." This causes her to bark lowly, head lowered to her shoulders, hackles raised, with some growling and bared teeth.
But remember. It is your job to protect your dog just as much as you expect him to protect you. I would never use Koda's protection command if I believed a person had a weapon (like a gun) because if they were determined to get to me, they would just shoot her first. And I could never forgive myself for that.
Mom To~ Dakoda (b/t GSD), Acheron (black GSD)