Speaking from our experience..
Keys:
-Sign language, learn the 10 most basic needs (food, potty, more, thanks, water, etc). They can use their hands before speaking
-Sit them on the toilet when they are young, they have to have some sense of what it is. Don’t wait until they can talk about it. While they are sitting, use signing and words and point to explain what is going on. Read to them while sitting (sometimes up to 30 min), if they start going, cheer/sign/talk and give them a treat! Start making the connection that this is a great thing.
-Have them walk around with no pants, as much as it is annoying to clean up, they have to get some feedback as to what is happening to them.
-Don’t use super absorbing diapers, we use reusable diapers for cost savings, and because the children can then feel wetness down there and start building a feedback loop of cause and effect. (we use disposables overnight to reduce rashes)
From experience in our friend group, if you wait until 3 y.o., they can start using potty as a tantrum/power play (not good).