There is a lot of information on the beginning process of learning to fly R/C planes, right here on R/CU.

I think Campy's estimation of the average being 3-4 months of Saturdays and Sundays to be too long. I think due to the exposure to simulators and computer games, this average is likely considerably less, now-a-days. Age, definatly is a determining factor. On average if you are younger, you will learn faster then if you are older. If you hook up with a good instructor, you will learn faster than if you hook up with a poor one. Many variables come into play.