Ask HN: A potential employer said he will get back to me, how long do I wait?

I'm in this position at the moment.

I have contacted a potential employer, a cool little startup I would love to help out, by sending through a cover letter and my CV. The founder got back to me and said he was a little busy and would get back to me when he has a chance to read through my specs.

I'm now in the process of tossing up how long I wait before sending a polite reminder. It has been over a week now, is this too short a time to push him to get back to me? It's fine if he is busy and still hasn't gotten time to appraise me, but what do I say as a gentle reminder without seeming too pushy or needy?