You can't, not accurately. Everyone gets this wrong regardless of whether the business succeeds or fails. From your post it sounds like webmasters with "search

You can't, not accurately. Everyone gets this wrong regardless of whether the business succeeds or fails. From your post it sounds like webmasters with "search boxes" are the ones who install this. So first estimate how many of these there are and what their traffic is. Then make up a nice-sounding rate for market share growth and plot it. That's really as far as anyone can tell you. You are the one with the most information. That process is useful because it forces you to really think about how your cool tech will actually operate in the real world. Why did your advisors tell you to go after dumb money first? What was their reasoning? There is a problem with "dumb" money -- it's not as useful as "smart" money. They can't do anything else to help you (contacts, expertise, advice) except write a check.