StepGrab: Offer discounts to only new customers

Hi, I'm a founder and currently applying to Ycombinator with this. I've just launched it. Looking for feedback. If you're a small business or have someone in family who has a small business and need new customers, then Great news, I'm offering Early Adopter discounted Pricing. Groupon failed because small business are not skilled enough to do calculus of optimizing discounts to maximize profits. Stepgrab doesn't offer unlimited discounts. It lets you give one time discount to new customers, using their phone number. Users sign up using phone number, app keeps track what discounts they have used and they don't qualify for it again. Unless business owner wants to retarget them. https://stepgrab.com