I definitely agree with most of your points especially understanding and using the product. It would infuriate me when people would walk into a Zipcar interview having never even considered signing up. My only concern is how long do you wait after starting to use the product before reaching out? <1 week shows you signed up just for the interview, a month seems reasonable but too soon to say you're a super user, while anything longer means you're spending less time w/o a job...unless you're still banking.
