We are a startup making our first hires. We are three founders, who respect each other hugely, help each other and forgive mistakes. We've been thru a lot together.
We raised money and are looking for core hires. Given our personal bond, we would like the core team (first 3-4 hires) to share our passion to some degree. Perhaps naively we'd like them to become pillars of our company and help us inspire future employees.
A former colleague of mine came forward, very bright and capable guy. Exactly the technical talent we need. He likes the project, but he offered to work three days a week for us because he would like to continue working on personal projects in parallel. While I appreciate his honesty, I cannot easily decide if he is the right kind of first hire. Had he joined us a year later, I would hire him in a heartbeat. But right now I feel like lack of commitment from him could possibly influence our culture in a negative way. Is this a right way to think about first hires? What would you do?
In your case, I think the issue is not about part time, but the commitment itself. If it's your first hire, you need them to be on-board, and contrary to what most people say, have more expectations than people would for a "normal" employee. The truth is, that person is not a normal employee, it's the first hire in a very early stage business. If you treat that hire as a regular employee, you will build expectations and won't be able to live up to it, and it will backfire for both of you 6-8 months down the road. That will hurt your ability to build a core team, and you will have to start from scratch.
Do not give up on that, no matter what the popular opinion tells you. Most people are not founders, and you should trust the guts that you have about building your core team.