I feel like too much time will end up with us being like brothers, and too little time will end up with the relationship being forced. I get a warm feeling every time my crush(?) calls me, so I may like him, but IDK. He said sure, maybe if we get to know each other more he'd date me, and I agreed. But how long into the relationship before I consider dating him?

There's no one-size-fits-all answer. Most people but by no means all people step through stages of confirming mutual social attraction, then romantic attraction, and finally sexual attraction.

So start out with hanging out as friends, and if mutual chemistry or "sparks" don't manifest then you just have a friend, and can look elsewhere for romance and sexual attraction.

It will help you a lot to figure out whether you're demisexual and what your needs and expectations are as far as exclusivity.