I kept waiting for my son to be ready but by 3 and 3 months (and preschool 2 weeks away) I was done waiting for him. I got this book and the doll. It was an intense experience, but it worked! I did nothing but potty train that day. No cleaning, cooking, talking on the phone, errands, etc. We potty trained and played all day. By noon, we went through 20 undies and I was ready to give up. It was extremely hard not to show frustration. But, it was as if something clicked because after noon, he only had one accident. The following day he had 7 or so accidents and by day 4 he was accident free.
I did my best to follow the method exactly, but the doll part didn't work. My son became jealous and angry towards it so we put it away. So, don't worry if you don't follow it 100%. It can still work. It's a lot of work and frustration, but it feels great to be done with diapers.