Here is a list that indicates a child is ready for potty training: She's able to walk well on her own, and can pull down her own pants (elastic waistbands are good for this) and diaper.
She shows that she's aware of what's going on in her diaper-- either by saying something like "poo" or by looking uncomfortable when her diaper is full, or pausing in her playing.
She's interested in what you do in the bathroom, coming in to watch from time to time. She might help to flush, or wave "bye, bye" to the departing poop.
She's not completely caught up in needing to say "no" to everything you suggest (the automatic "no" stage is usually between about 18 and 30 months.)
She has tried to sit on the potty, with her pants and diaper on, and doesn't seem to mind it. She feels "friendly" towards "her" potty.
She understands when you ask, in a mildly interested way, "Do you need to use the potty?"
She's fascinated by putting things into containers (blocks into the box, pouring sand or water in and out of a bucket.)
She feels proud when she can do something "all by myself."
Her diaper is dry and clean often for a couple of hours at least.
She's interested in "big girl underpants."
Most kids show some interest before they are physiologically ready to potty train. I would get him a potty and let him get used to it, but I wouldn't push it since he's so young.