Late to this thread, but anyway -
dd, tried at 2.2yo, she was sorted in 3 days and dry at night 6wks later, was a doddle, didn't know how lucky I was. She showed no signs of being ready though, I just thought I'd try.
ds1 - he had no idea, he used to stand there weeing over his feet and carry on playing, oblivious. At 3.4 I knew he had to get it because of starting school 3 months later. He didn't want to bother, so I promised him a Peppa Pig Rocket . He got the idea of going on the potty fairly quickly, and was fine as long as I told him to go and sit on it. It took over a year to get the hang of remembering to go himself. Although he has never had an accident at school - they remind them a lot there! If I'd waited for him to want to do it, he'd still be in nappies (he is 5.5 and still complains about having to stop playing and go to the toilet).
ds2 - he is 2.5. We're tried recently - he is keen, and very good at knowing he needs to go, and gets to the potty on time - but he needs to go every 15 minutes. So after a fortnight of thinking he'd get better and go less frequently, I gave up. He is doing poos in the toilet though so that is something!