Hellos. Well, the keyword here is "too". You think he's too old. He's not just old, but too old. Too old for you. So if you are thinking like that, I doubt you are going to be prepared to be in a relationship with him.
Apparently you are seem uncomfortable with this situation. If you are not, you wouldn't be thinking that he's too old for you, you would simply be wondering if the age gap is too wide instead of viewing him as too old.
So that's not good and I think it's best if you are not going to be in this relationship.
But then again, not to fret, it's your own choices and I would respect them.
If he treats you as if you are his girlfriend, it means that he already feels as if he's in a relationship with you although it isn't official yet. That's a good sign, it shows that he's into you. Although if you feel uncomfortable about it you can always tell him that he might be going too far.
And he seems pretty responsible too, if he's not willing to date you when you are still young and is willing to wait till a year later. If he says that, it means that he does want to be in a relationship with you. Because if he doesn't, he would have just walked away, so don't worry.
Good luck and all the best with your relationship! =D And you can message me anytime if you want someone to talk to.