I read that you can start around 18 months on the average. So I tried on month 18, he was thrashing when I tried to sit hin on the potty, I waited then I tried then waited.
At 2 years and 4 months I decided to try again and do it step by step. Sit down on the potty every morning just to get him used to the idea of the throne- then, I introduced the step stool and had him stand up and let him stand. The first few times he cried and when I turned to help out Kimi with something I find him beside me with a puddle- away from the potty. It took a few more tries to get him to stay near the potty and not follow me around when he was supposed to be doing his thing.
* Finally, a success!
Now, he is not that scared of the potty seat anymore and I realized that he likes to stand and do the potty instead of doing it sitting down. I was so happy that he doesn't think of the potty as the enemy anymore and decided to show hubby his progress. I asked Kenzo to go to the potty and he relented, stood on the potty. I was surprised when I heard a swiisssh.... Was that a pee? Then after a few seconds- swiiish. An unmistakable pee right into the bowl! I know it's was a small progress but I was happy that Kenzo decided to do his first pee in the potty with us two in there to witness it.
I guess you can't force everything to conform to what you want should happen. It will happen when the kid is ready for that milestone... Just wanted to share this little privy information. Pardon me for sharing a bathroom story ;)