Minimum viable audience
The minimum viable audience is smallest number of customers needed to make your business work. Using this methodology helps focus the work and proves more meaninful than projecting a massive number a business could attract if everything goes right.
Seth Godin discusses the concept of minimum viable audiences in his writing. He writes that by focusing on a small audience, you are forced to delight them. This pushes the product to be better because there's no other audience available. Rather than looking for another customer, the product gets improved until it serves that audience in a vital way.
And once the product is great enough to delight the minimum audience, the audience grows organically. It's likely a bigger audience than imagined, and the delighted customers will naturally spread the word to others.