I am taking 8-10 months to build the business infrastructure after taking 2 very intensive years of practice (including being a second for a pro wedding photographer for 4 weddings).
I would have to say that my focused practice shots are easily over 2 terrabytes of RAW only files and will continue to grow likely to well over 3 terrabytes before I feel I am ready to open in fall 2009. This is a small aspect that many new business owners forget (getting as good as you can get)... that and having a business plan.
If I wanted to start tomorrow, I would already have a clientele that would give me something between $1000-2000/month just playing on the side, but nothing is being sold or taken until everything is in place. Right now my consulting business gives me significantly more than that, so it will be a long time, if ever, that I would go into full time photography.
The
business of photography has very little to do with pressing a shutter!
How much money can one make? How much can one make in ANY business? Anywhere from zero to millions. The real question is... how good are you and what are you doing on the business end to differentiate yourself from the competition? In terms of making money, being good in business is more important than being a good photographer, though ideally one would want to be both.