Looks like we're in together on this
I'm starting to potty train my son too. He is 21 months now but we have been so busy that we have not't really done a lot to train him. He doesn't like to wear nappies much anymore and he knows he has a potty and pretends to pee and poo in it (but still hasn't). Sometimes we put him in underwear instead of nappies so he can feel wet if he pees, and also so we can pull them down easily to bring him to pee... so far no success peeing in the potty but he does know when he pees and poos and will tell us.
They learn by imitation as well so let your son see you on the toilet and tell him you're peeing or pooing...they get the idea