My daughter was around 37 months when she was fully potty trained. This is how I did it. From 24 months about every 2 months we would try under pants. She would be fine and I would continue asking her-do you need to pee. Well then she would pee her pants and I would say-nope, not going to do this. So just continued trying the panties if she would have an accident I just felt she wasn't ready. A month after she turned 3 I put the panties on her and she started going-without even telling me. Just went to the potty and peed. Have had 2 accidents in the past 4 months-just when we have been out busy and not even thinking about the bathroom.
So yeah I am all for waiting until they are ready-it made much less stress for me. If you are wanting out of diapers sooner-I am not the one to give advice on that, but they will usually let you know when they are ready.