I started mine on raw at eight weeks, but I had a lot of "raw" experience previously having fed it to dogs for years.
You are going to need to do quite a bit of research to get it right- it is not just a matter of giving them pieces of raw things- mineral balance is especially tricky, and some forms of raw meat (rabbit) carry more of a parasite risk than others.This site
is a good jumping off place for your research, and there are numerous other sources online. I particularly recommend the "RawCats" group on Yahoo.
There are also prepared raw foods available that take the work out of the equation- Aunt Jeni's
and Feline Future
come to mind.