My youngest son was two years old when we started fostering him and his 4 year old brother. We lived in the farmhouse in the middle of nowhere. The older kids and I thought it would be cool to potty train him by letting him pee outside on a tree or lean against a tree to poo in the woods. He thought that was soooooo cool and pretty soon he'd go without his diaper just so he could pee and poo on a tree. All was going great until my wife found him peeing in the pot of an indoor floor plant. Her solution was to paint a tree on the underside of the toilet lid and bam, he was potty trained.
Oh, congrats to Jr Yin on using the toilet. That is a big step.