1. Create MVP (0-100hrs work max) without talking to customers (too much) avoids paralysis. Avoids mum-test type issues too. Have some basis that it is a good idea (e.g. competitors, solving your own pain, a pain you see mentioned alot online)
2. Get MVP in front of people then talk to users.
3. Iterate based on that information: talking to people who are taking time to use your service.
It is a nice filter to talk to people who use your service (proof of work!) vs. just interviewing a bunch of people who look like they might be in your persona.