Hello D....First I want to wish you the best of luck with the potty training adventure.
I am the mother of 4 children soon to be adding number 5 and I have found that with all of my children each were very different from when they were ready. The little girl by far the easiest to train.
First thing I must tell you is be very patient with him. He'll get it! And keep plenty of vinegar handy to get urine out of the carpet/furniture/mattresses..hehe!.
My third born son by far proved to be the most challenging of the four children to potty train. I did the pull up thing just like you are doing and eventually figured out that the best way to go was to put him in big boy underwear. The pull ups seemed to give him the security of a diaper (ie If I wet myself the pull ups won't make a mess)so we finally just took them away and said no more. He would fuss and raise the roof, but we stuck to our word and refused to put another pull up back on him.
Adventually, after a while, and much time on my hands and knees cleaning up the little accidents he finally started to get the "feel" of when he needed to go pee in the toilet.
We started out with every 1/2 hour or so putting him on the toilet and taking some warm water and pouring on his belly just below the belly button to help stimulate the urge to pee. Then we would build up the time in between.
One of the things that we also incorporated into our "training" him (some of you may not agree with this method) was when Daddy went to the bathroom he went with daddy also. It really helped him "figure" things out.
If your tiny tot wets himself keep telling him it's okay and that accidents happen. During the little chat also tell him to remember what it felt like before he had his little accident and when he feels that feeling again to go to the potty. The key to the training is to be consistant.
Best of luck to you all.
D.