Potty training at 6 months sounds like the masochists approach. Why would you train before they can physically get on a potty? Yes, they pee all the time at 4 months, do they really gain much being held on a potty?
I don't want to plop a baby in front of TV but likewise I wouldn't want their early months to be all about the potty.
When they're ready, if they've had a rounded start to life it's a just another simple transition.