Well, it is tough for me to really tell you what to do because I am far from an expert and every kid is a little different. I do think that he is ready, but you need to be ready. If you are ready, this is what I would suggest, only because this is what worked for us and I have a son, like yours, who likes to do things at his own pace.....
1. The day we started, no more wearing jeans, elastic waist band pants only so he can learn to pull his pants up and down on his own and we put him in real big boy undies, NO PULL UPS, they are too similar to a diaper. We had the "Big Boy" talk and there was no turning back!
2. Watched the clock. I took him to the potty (and he protested EVERY TIME for the first 3 days) every 45min. or so, Realistically, he only ever really had to go every hour and a half or so, but it was more a routein at first.
3. If he didn't have to go, which he never had to go at first, I made him count to 10. when he got to 10 he could get up. and we tried again later. This helped him with counting and learning numbers so that was a bonus because now he is counting things all day long.
4. If he went pee pee, he got 1 M&M and a sticker for his potty chart. He loved the praise. If/when he had accidents, we went over the "Big Boy" talk and I would ask him where he goes pee pee, and he would tell me the potty so I knew he was getting the picture. He got new undies, had to sit on the potty, count to 10 and then we woudl try later.
The first 3 days, as I said, were hard. He probable only went on the potty 5 times in 3 days. I was ready to give up and convinced that I made a bad decision because he just was not ready. Well, day 4, not one accident all day and he was now telling me when he had to go ~ no more watching the clock.
It was tough for me to push him and easier for me to say he wasn't ready because that was best for me........that was just it, it was ME. As soon as I decided that I could PT him, he did it. So you need to first make the commitment to do it, set up a plan that you think would best fit your child, and no mater how tough, stick to it. You will have to insist or push a little, but he will catch on and if he is praised for it, he will want to repeat the behavior and you will not have to push anymore.