This has always been a interesting topic because there is no right or wrong time to start potty training. Check out this video from The Dad Lab
With Haylee, we started potty training around 15 months but only because she started motioning she wanted to use the potty. We never pushed her to do it. She went through stages of wanting to and then not wanting to. She was doing really well and then Sarah was born. She went through a phase where we had to put the pull-ups on especially at night. She was about 3 1/2 and she finally was potty trained. Sarah is now almost 2 and she takes her diaper off and goes and sits on her potty.
The key is not to scold the child for accidents. It is not their fault. Do not get angry with them if there are accidents. Work with your child. He or she will eventually be potty trained, just keep working with them!