"Should I take initiative and ask him out or wait for him to do it ?"

If everything is going great and you have no doubts then yes go ahead and ask him out. Who says that girls can't ask guys out.

But if you are hesitant and don't want to be let down then maybe subtly bring up the topic of "being together" and see how he reacts. If he reacts well and seems to really like the idea then go for it, if not maybe you should rethink the situation.

Maybe he's scared of being rejected by you so he's waiting, so I say take initiative whether it's being straight up and asking , or taking small steps and hinting it.