We introduced the potty in infancy. It saved us some diapers and poo-splosians don't happen when the poop is in the toilet. In toddlerhood we did diaper free time (with pants on). We also taught the sign for potty. Violet learned to say potty before she learned to sign it and was requesting it consistently by 18 months... Then she stopped around 19 months. Between reading her signals and her sometimes asking, she was out of diapers again at 23 months. She had ups and downs with accidents, but it was good enough until about 2 years 5 months when she had a complete regression and went back into diapers. A few months later, we told her we were buying no more diapers and that if she used a diaper, she needed to change it herself (pull-on style diapers and help with poop) and that if she used the toilet, she would get a chocolate chip. I don't remember the exact timeline, but I remember she was upset for a couple days and then was basically on-board with it.
We started out the same with Leo, but a little more relaxed. He was using the toilet regularly by 23 months but when we went on vacation around his birthday, he stopped. I tried potty training at about 2 years 8 months, but my husband who is a stay at home dad, did not follow through throughout the week, so it didn't stick. My strategy was cold turkey on the diapers and chocolate chip for successful potty use. I tried again a month later when I had 2 weeks off work and my husband was ready to commit to it. It took longer this time around and there were near constant "accidents" for about a month. By about a month and a half he had it down pretty good.
Edit: oh, I forgot that with Leo, we used a timer for the first couple days. He stayed pretty dry on those days, but I didn't stick with it. I just did it to give him a boost and so he had a chance to experience what he was working toward.