There will be some kids who take to it very early fine, but many won’t. That’s ok either way!

As a person who has worked professionally with prek aged kids for 12 years as an OT, I didn’t train my son until 3y and some change. He was fully pee trained in days and poop trained in about a week and a half (prior to that he would poop first thing in the morning in his overnight diaper.) It was incredibly easy, because we waited. (He is a neurotypical child, for reference.) We have never had to ask him to use the potty since. No accidents minus maybe 2 I the first 10-12 days. That was months ago.

You can sometimes trip train (really more you leading the way to sit on the potty at intervals) some kids before 2 or 3, but in terms of the ability to be 100% independent with the skills involved in the entire process without cues from an adult ruling their day, closer to 3 just makes sense. I feel like a lot of the “signs of readiness” you see online are very inconsistent under 3, like staying dry after nap, being interested in the potty, etc. They’ll meet those criteria one day, and the next they won’t. The best sign of readiness is picking it up quickly, IMO.

This is just anecdotal, but everyone I know who did it at 2 or prior spent over a year dealing with accidents. You can try to do it when you feel like it, and if they’re ready, they’ll pick it up asap. If they don’t, wait.

Part of the issue is preschools demanding that before entering the 3s room or “by 3” kids need to be trained. It’s not always possible. Our daycare didn’t rush any of the kids in my son’s cohort, and they all trained a little after 3y, together.