From my own experience I would say hold off on moves towards PTing! My dd was the exact smae way- at 19 mths she got a bad tummy virus and would get up in the middle of the night nad beg for the potty to go poop on, and she was peeing in it everyday, of her own accord. So I tried training pants and potty-training her, and it back-fired.
To make a long story short, she is 28 mths now and almsot fully PTed, but I wish I had just encouraged the potty without any true PTing, like the training pants.
So, I'd say just make a quick, happy comment to show your approval when goes potty but don't make a big to-do over it- this looked like it worked for my dd, but really just turned her off. At 19 mths he is most likely not mature enough to stop playing and go to the potty everytime he needs to.
The good news is that with the gentle encouragement but no pressure, he may very well PT by 2- 2.5! I say they do it when they are ready and all you really have to do is stand by and offer simple praise and talk about the potty.
Also, the Bear in the Big Blue House video "Potty Time with Bear" and the "once Upon a Potty" book are both excellent, cute, and factual resources to help him out!
Good luck, you will have to feel this one out and you both will learn from the experience!