In the early stages of your product journey, you won't much (if any) data that suggest your product will be a success. However, you should have confidence that there is a potential business behind the problem you are solving, and that other people want that problem solved.
If you feel that sense of confidence, you should continue to move forward and spend energy on gathering quantitative information that there are more than 5-10 potential customers. Think of this as high-level market research. We want to gather quantitative data to build more confidence that there is a market interested in your unique value proposition.
We want to put our idea in front of as many people as we can, as quickly as we can, and learn if those people resonate with the problem we are solving and the unique value proposition. There are three questions we want to answer:
- How many potential customers identify with the problem?
- How many potential customers will investigate into solutions?
- How many potential customers will commit to a currency exchange for a solution?
To answer the above questions, we can run a variety of experiments that reach a large audience, elicit a behavior from individuals that demonstrate an interest in your unique value proposition, and solicit a currency exchange from individuals in that audience to demonstrates a willingness to pay for a solution.
Assuming you have already done your customer development (if not, get out of the building!), a next good step might be the Google Keywords research method. This should help you build more confidence that a larger audience is looking for a solution to the problem you want to solve. A more advanced experiment to get a far better sense of validation is the Facebook/AdWords Ad Experiment. Probably the best validation experiment you can run is the Fake Door experiment.
Most products fail because nobody wants them. Don't be that person - do some customer development and idea validation before you spend so much of your valuable time building something nobody is going to use.