My little boy (2y 5m) took it upon himself to toilet train about 4 weeks ago. He just decided that he didn't want to wear nappies any more! I wasn't in any rush but decided to go for it.
It's been bloomin' hard work but we've finally got there although we do still have accidents on a regular basis. I also find that I have to watch him and insist on him going to the toilet when he's 'fiddling' even though he'll often insist he doesn't need to go!
I did read that you don't bother with the whole standing up thing til it's well established - in fact Oliver can't actually wee standing up yet! If we're out and he has to go in the open air he needs to squat to actually go.
I guess my advice is to wait til you absolutely feel he's ready or until he forces the issue - I nearly gave up on several occasions and wish he'd waited a bit longer TBH.