The best starting point to find people to interview is your network. And you've likely already talked to some friends or family about your idea! The key here is to make sure that you're not talking to just anyone, but specifically customers. If they don't fit your customer persona, then you should not be doing customer interviews with them. However, if they have expertise in certain areas, you can do expert interviews with them (we'll be covering that in The Expert Interview).
If your network isn't rich in these types of contacts, you'll need to extend your search to your second-degree network and tap into the "Channels" section of your Customer Persona. Remember, this section is about what the customer is currently doing to solve their problem and where they spend their time, either physically or virtually.
B2B can be especially challenging. In addition to your personal and professional networks, consider looking into these channels: