directwheels - 5:12 pm on Nov 9, 2010 (gmt 0)
Depends on your niche. I have had success instantly with PPC, but that does take some luck. I have had sites that had to wait about a year to start making money.
The key for me is to start a lot of project and like the saying goes "throw !@#$ at the fan and see what works", you will be surprised at what works and what doesn't work. Test, test, test!
In terms of scaling up to a full time income, I have had projects that took 4-5 years, but was lucky with one particular project that took 8 months. Of course, a lot of projects that never made more than $200 in a year.