After a while, a CTO contacted me and asked if I could "support" his team and add some features that he wanted. After a month of sweating, we agreed that they'd pay me a monthly support subscription of $2k.
I learned a lot from the use cases, improved the software, and got some more users, which ultimately was enough of a story for VCs to raise a $3M seed round, which I think is quite cool as a first-time founder from Germany with zero connections, no YC friends, etc...
I quickly realized that I could not pull this off alone, so I teamed up with 3 fantastic Co-Founders who are responsible for the business side, marketing, sales, and engineering.
Fast forward two years and we're growing our customer base at a great pace and are slowly looking towards a Series A. I can tell though that the way from our first customer to where we are now was extremely tough. We're in enterprise sales, we had to switch our strategy at some point. Lots of learning, lots of pain.
In retrospect, I wouldn't say that the first customer is the hardest. Building a repeatable sales motion is much harder. Building a product, marketing, and sales process that all aligns well for repeatable sales is a lot of work.
Whoever tries this, good luck and please connect if you need help as a founder or want some advice. I love to help others to start their own business. It's hard, but it's also a life that I don't want to miss.