Hi M.,
We just finished potty training our 2 yr old girl/boy twins in the last few months. I did my daughter in November and my son in January just to make things slightly easier. I followed my own timer system. (I did this with my firstborn, too, and it was WAY easier with just one!!) I swear it's more of a parent commitment than anything else! I told them we were getting rid of diapers and took them to the store to pick out underwear and a cheap digital kitchen timer. Basically, I get them to the bathroom first thing in the morning and set the timer for 45 minutes. So we'd go every time it went off. By the end of the first day, it was clear both (though this was happening at separate times) could make it over an hour. So by the end of the week, the timer was set for every 90 minutes to 2 hours. They wore underwear all day and a pull-up at night. They got 3 Smarties for peeing and 3 M&Ms for pooping. After 2 weeks, we didn't use the timer and could go out on any errand comfortably for about 2 hours in underwear. However, I still set it occasionally just for myself so I didn't forget to make them go! Also after 2 weeks, I noticed they were ALWAYS waking up dry. So we did 1 more week of pull-ups at night and then they slept in underwear. My daughter had one overnight accident when she was sick and fell asleep very early without going to the bathroom first. My son has had 1 overnight accident, too, and again only because we were out later, he fell asleep, and we didn't take him before bed. For me, this was REALLY an easy method, but in the first week, it felt like a big commitment on my end. After 1 week, they started to tell me they had to go or they'd show signs that I could pick up on. After 2 weeks, they both told me all the time if they had to go. We dropped the Smarties & M&M rewards after the pull-ups were gone at night. They did miss that, so we did a daily treat after dinner for the whole family - like a Hershey Kiss for everyone - to celebrate waking up dry and using the toilet all day. My twins will be 3 in May and it's SO nice to not have diapers or pull-ups!! The important thing for us was to be consistent, explain the plan, give tons of praise, and NOT go back, even if it would've seemed more convenient for us. With my older daughter, who is now 7, I did basically the same thing and the entire process, including no more pull-ups at night was only about 2 weeks. I think now I'm just older & more tired and couldn't keep up with both of them on the same time table!! When it was all over with, we took the entire family out for a big kid celebration dinner at Chuck E. Cheese, which my daughter appropriate named - The Potty Party. Just some ideas... Good luck!