For a SaaS we launched about 7 years ago, the initial people came from LinkedIn, so my suggestion would be to look for people on linkedin that fit your target profile and ask them for a bit of time to discuss their workflow/issues and how they are fixing them now. If not linkedin, find where people that fit your target profile hang out online (is it a sub-reddit, is there some kind of forum?). if not online, try to find an actual conference and visit it, chat to people in the hallways.

Don't pitch the product, talk about researching for the product (which is what you'll be doing anyway, but some of those initial interview people may become your best advocates). People that genuinely have the problem you want to solve will want to help.

Steve Blank has a nice segment on the ideal people to involve here in The Four Steps to the Epiphany, calling them Earlyvangelists. One big thing to look for is that people have identified a problem that you're solving, tried to solve it themselves, and in an ideal scenario have a budget for a better solution (see https://www.votito.com/methods/earlyvangelists/ for more).

_The Mom Test_ book is an excellent interview guide for this stage, and you'll figure out the questions to ask from there. here's my checklist from when I used it a while ago (not verbatim from the book, so best to actually read the book).

- how do you currently solve X - and how much time do you spend on it? can you show me how you do it? - what happened the last time X came up? talk me through the last time it happened. - if not solved, why not - have you tried finding a different solution for it? - why do you bother doing it? - what are the implications of that? - what else have you tried? - who else should I talk to? - anything else I should have asked?

to find if the problem you want to solve even matters at all: - how much time do you spend on it each week? - which tools and services are you using for it? - what have you already tried doing to improve this? - what are the 3 big things you’re trying to fix or improve right now?