Hi Y.,
Its been a while for me since I potty trained my son, he is now 11 years old however I'll tell you my wonderful experience potty training.
I know all kids are different and I'll be honest, I felt almost cheated out of the potty training phase, I bought that book "Potty Train your Child in Just One Day" more because I had seen nothing but lots of accidents and grief with my friends when it came to potty training there children, so I bought the book almost as a joke to myself to see what they really had to say that they think would work, I was pretty pessimistic about the whole thing, but I read it, felt like it kind of made sense and gave it a shot.
First of all, I bought my son a potty toilet for Christmas when he was 1 year and 9 months old, his 2 year birthday was in march. I pulled it out of the box just to check it out and set it in my hallway next to the bathroom just to store it until I "Saw the signs" of him being ready, what ever they looked like, I didnt have a clue. I read the book for clues and one day before his 2nd birthday, I found a poopie in the training toilet, I thought "could he really be ready?" so me and my "yeah, right!" attitude went for it, I followed the book exactly, (that way if it failed I couldnt blame it on me not following the book as suggested) and at the end of the day, I genuinely felt like "How could it work, he was in diapers this morning, underwear now? No way" but it said once you put them in underwear, don't put them back in diapers. So I put him in his underwear and I absolutely Promise you, my son has never-ever had an accident, day or night, he was trained in just one day. Boom! It was over, no more training. It was like I skipped that part of his development. I was shocked.
I also feel the need to tell you that my son didn’t even start talking until he was closer to 3 years old so I don't know that they have to be able to verbally communicate before potty training. In our case, He didn’t. and because of his lack of communication he had one night time accident where it was my fault, He woke up crying because he was trying to take off his zip-down one-zee pajamas and I kept holding him to calm him down, he kept pushing me away and tugging on his zipper, then he finally went because I didn’t know he was trying to go to the bathroom and wouldn’t let him go, I thought he was having a nightmare.
I recommend this book often on this site because of my pleasant experience with it. I still dont know why it worked so well nor do I know if it would work this well on all children, but I at least have to tell about it. I have actually applied the techniques from the book to other learning areas in his life. It was great enlightenment.
Best of luck to you and your sweet twins.
Oh... One last thing I wanted to say, My son never did use the potty training toilet, he went straight to the house toilet, I just had the smaller seat attachment and a stool for him.