Where to start finding your first customers?

I read an article about Product/Market fit from Superhuman's CEO.
https://firstround.com/review/how-superhuman-built-an-engine-to-find-product-market-fit/

They have this process which is basically arise from a question what if you could measure product/market fit? They created product/market KPI.

This was really impressive process but we're not at that stage yet. Thus, we created a basic process. This process helped us to find valuable insights where to search our firs users and where to communicate with them. This is a way to clarify a lot of points when you're just starting off. However this article for beginners or even the ones who are just starting off.

I hope you like it.

Article: https://medium.com/jooseph-blog/how-to-create-a-behavioral-change-out-of-a-problem-12f1011ab8d0