I gave a presentation on "how to find a co-founder" several times. Guess what: by slide 2, I give away the answer: the best co-founder is someone you already worked with. Not helpful? That's the truth. Instead of trying to find a co-founder quickly, find a good contributor to your project. They may grow into becoming a co-founder over time, or they may "just" be your first employee. No one can really tell until time…
> ... the best co-founder is someone you already worked with. Not helpful? That's the truth. Not really. I started-up with a co-worker (of 2 years) and a guy whom I hadn't worked with before and guess who was the first to bring problems to the company and quit? The guy I previously worked with... Truth is you don't really know a person until you're both in a seriously f*ckd up situation. That's what my experience has…
Going with a stranger might still be a good option if e.g. your previous company had bad quality staff, or if you were a business person and never had any contact with any technical people, but it's still akin to playing roulette.