When to bring on co-founders? I will not promote

I've taken my idea as far as a I can. It does not have a lot of revenue, but it's a good idea that could potentially scale (10+ paying customers) I know I would need hardware engineering + commercial growth. How do I know the idea is good enough to actually bring on other people? I know I need commerical/hardware people, but how exactly do I communicate my vision to them + what I want them to do? Or is it more of a team effort? Can anyone here share their experience actually working on a startup team?