About 8 months. And another 6 months, or so, to one (modest) salary profitable (meaning: enough for one person to live normally, without money concerns). We're probably at two salary profitable today, though it's a bit weak for a Silicon Valley engineer salary, and my co-founder has a family and a mortgage (in the valley).

We were actually selling software within a month or two of starting the company, as we were starting from a mature Open Source project and so didn't have a ton of code to write, so we hit the ground running pretty fast.