when to switch to pull ups

Steph

we have boy/girl twins that will be 2 in July. They don't tell us when they have to go potty yet and they're not too interested in sitting on the potty either. our daughter has went pee once on the potty after bath. she was pretty upset that I had to put a diaper on her afterwards. we have little potties for them and we have a seat for the toilet that we need to install and some potty books. we are expecting another baby in November! we are hoping to have at least one if not both potty trained by then. we're not sure when to switch to pull ups to make it easier to try to get them on the potty more. how long are kids typically in Pull-Ups? Any tips to get them more interested.