Probably about 9 month to 12 months as he enters maturity. All dogs are different of course, and just because the breed has a tendency, individual dogs wil develop all sorts of different personalties from that standard. If it is purebred and you got him from a breeder take a look at the parents. That is the personality that your dog is most genetically predisposed to. The rest of his personality will come from upbringing.

When you visit this site, go to "Akita Information" and scroll down to whatever you'd like to read about.

Most likely around two years of age (at social maturity, not sexual maturity…which happens much earlier), but keep him social as long as you can…there's a difference between protective and aggressive. A common mistake people make is keeping such breeds away from people…fearing they won't be protective. They don't realize they're puppies and simply haven't matured. Seriously, watch around age two. BTW, my Catahoula was the same way, adored everyone! A couple months before he turned two, he suddenly was no longer interested and becoming protective. I'm very thankful I took him to 'social-dog' classes and got him out and about as much as possible those early years. He won't have anything to do with others now, at all. I'm convinced, he would have become aggressive had I kept him away from the world.

I wouldn't worry about it, if I were you. I think if the time ever came when he really sensed that you needed protection, those behaviors would probably kick in as needed. Be glad that you have an outgoing dog; spend a lot of time socializing him and teaching him to interact politely with other people. If someone or situation makes you uneasy, he will pick up on that. Your body language will change, and dogs are very good at detecting even minute changes in your posture. Also, if you become frightened or anxious, the hormones your body releases will have metabolites that will come out in sweat and on your breath. They can smell that easily. If you're his leader, and his leader becomes uneasy, he will too. So don't worry about it. Just hope you're never in a situation where you need that behavior.

My boy was exactly the same at that age and I thought that I was not going to end up with a guard dog after all, but at about 6mth he slowly started changing, and when walking, where he would have gone up to anyone tail wagging, he started to become more aloof, and would ignore the strangers oohhhing and ahhhing at him. He now at 13 months is icredibly protective of home and family, and has a certain, "I really dont care and I really dont want to know you" attitude when he meets strangers now.
You should see this aloofness starting to come out in your boy over the coming months.

Oh he is actually an Akita too! sorry I just said my boy, could have been any breed