>I was wondering, as school start, should I play cool, and say Hi to him first, or wait for him to do so.

Good idea but there is one condition. If he don't answer you, give up (or in) and don't even try to talk to him. Never. It's hella annoying when people keep bugging you everyday with their "hello/hi/whatever" knowing you won't react. If he refuse to greet with you (remaining silent IS a refusal), he don't want to know you. Easy thing but lots of people don't understand this.

At least you will be know what he thinks about you:
a)silence - I don't want to know you.
b)answer - I don't mind you.

BTW: What do you mean by nerdy? Obsessed with one stuff (like some mad scientist) or unsociable?

PS.: Sorry for my English, guyz. I know sh!t about Its grammar.