The child lets you know when they’re ready.
When they wake up dry from a nap they are ready to start. Put them in under ware, helps them understand what’s going on, pull up’s for bed time or car rides.
Nothing wrong with starting now. But don’t get frustrated if it still takes a year for him to be completely potty trained. Each child is different. Never compare your child achievements to another’s.
I started my daughter about a year and a half and she was fully trained, minus a few accidents here and there, by the time she was 3. Definitely encourage now but don’t force. 
I started mine when they refused to let me go to the bathroom by myself. Might as well give them something to do.
My daughter is 3 going on 4, we are still struggling with potty training. Each kid is different my nephew was almost 5 before he was fully potty trained, one of my best friends has bother her boys potty trained by 3. It’s all about what feels right for your kid. Remember you maybe ready to potty train and he might not be and that’s okay too
I started at 2 and he was trained by the time he was 3.
the only bad part about having a child be late potty trained is if they turn 5 and aren’t potty trained they cant start Kindergarten
They will let you know. Mine is stubborn. He knew how to use the potty and could hold it for long periods. He just didnt WANT to. I finally just stopped putting him in a pull up unless he was napping or sleeping for the night. One to 2 weeks of accidents and he was good and no longer wanted pull ups. I just made sure to send extra clothes and underwear to daycare.
My son is three I had been trying since age 2 he finally got it . Only had a few accidents doesn’t have them anymore. All kids are different