I think your cats are about the same age as mine, and I must say, I have not found getting them to eat the chicken easy, twiglet (who is only 16 weeks old) has had no problem. But out of my older 3 (all 10 months old) only one of them eats the raw meat properly.
I started with chicken breast (chopped) and then moved onto thighs / drumsticks / wings, but I wonder if it might have been better to start off with the drumsticks chopped up and just gradually made the pieces bigger. The reason I say this, is because they seem to have got a taste for the breast and wont change over.

Just as another hint, Murray loves tuna, so i drizzled tuna juice on his, worked a treat! I just gradually reduced the amount of tuna on his chicken. He is the only one of my older ones that will eat any raw I put down, including the bone - which is really important.