Just that. My 16 month old son saw his dad oee standing up a few times at bath time. He keeps trying to go towards the loo pulling at his bottoms. At bath time he's taken to standing up and peeing (if he needs to go) against the side of the bath (sort of facing the side that mirrors facing the toilet).
He's always hated a wet nappy (does not care about poo though :/ ) he's also pretty petite (25th percentile).
It feels far, far too young to be thinking about this - but I keep hearing people talking about starting when you get dyes from your child?