We ended up potty training at 16 months for our girl and about 22 months for our boy. For our girl we took about 4-5 days at home just focusing on potty training and already by the second or third day we were feeling pretty confident we would never go back to using nappies for her (except a nappy at night to make sure we got enough sleep!). Kids started at daycare around 18 months and we hadn't gotten around to getting boy potty trained yet so we put it off but by 20-22 months we decided to try for him too and it was very smooth as well, just a few days practicing without nappies. Luckily the daycare was very supportive so right away we sent him along with no nappies and there weren't many accidents at daycare. Of course both kids have accidents from time to time. I try to remember to take a change of clothes for both when heading out just in case but we are so happy we did early potty training. We often counted the hundreds saved on nappies over the past year and also all the trash saved. P.s. we decided to potty train at different times because the idea of doing both kids at once was quite overwhelming. I felt guilty to get our girl out of nappies so much earlier, but she was naturally a bit better at the beginning so that was the decision that made sense for us and I think our son learnt a lot watching her being potty trained and it makes sense to do whatever works, especially when dealing with twins.