Re: Wanting to switch - questions!
Congrats on the kitten! Starting on raw now will save you a lot of stress later, adults can be VERY hard to switch, kittens are usually easy.
You can start at 8% and see if he's easting it, if not cut back, if he's scarfing it down and wanting ore feed more. Kittens should get as much as they want. Just keep an eye on his weight so that as he approaches adulthood you can know when to start cutting back so he does not get fat.
I would switch cold turkey if he is willing to eat all of the ingredients (meat, bones, and organs) within a reasonable amount of time. If you find you are having a really hard time getting him to eat something, say liver, and it's been many weeks sine he's had any I'd add canned food back in so he is getting some of the vitamins liver should be giving him. But like I said, with a kitten it shouldn't be too hard, just make sure bones are nice a small, stick to cornish game hens or whole prey (mice).
The first time you give him raw I'd just start with small pieces (no larger than a quarter) of boneless, skinless chicken breast or thigh JUST to see if he likes the taste. Cats are often suspicious of new food so if it's difficult he might not bother. But once he's realized it tastes good you can start making bigger pieces. once he can handle a meal sized piece of meat with no problem start feeding meat with skin and then later bones until he's chomping through it no problem. Move as quickly as you can so the cat doesn't get lazy. As far as introducing different kinds of meat, you can do that right away too, but it might be good to wait a few days between introducing new meats in case there is a bad reaction (diarrhea), you'll know which meat caused it.
Organs can be introduced right away.
You can feed the 80-10-5-5 over the course of a week or daily, that's up to you. Willie needed one ounce of liver a week. I'd measure out one ounce and then cut that into 5 pieces, same with kidney. He got meat with his organs. The other four meals were bone (2 chicken wings, he could only eat one half of a wing per meal). If your cat likes organs you don't have to feed it with every meal, you can make the pieces bigger and feed them less often. Willie hated organs so the more I fed them, the smaller I could make them in hopes of hiding it amongst his meat.
Hope that helps you out a bit, tell us how he likes it!