This completely depends on the business model. When I started my first business, I no money saved up, signed my first mortgage 2 weeks after starting my business, and had my first kid 4 weeks in. I made money during the first month. By month 6, I was making just enough to support my young family of 3. We have never missed a mortgage payment and I now have my home fully paid off. This is called bootstrapping.

I've also worked with entrepreneurs who are building a business model that won't make money for at least 12 months - by design. This later scenario usually requires outside investment capital to work.