My DS is 16 mo and we always let him have a naked run around before his bath. He nearly always wees when doing this, once if not twice, and in the last couple of weeks has become very fascinated with the whole process - sits very still and watches the wee and then solemnly informs us (i.e. hollers "wee" at the top of his voice) that we might need to mop it up.
DH and I weren't really expecting to potty train for about another year so are a bit uncertain as to whether this is a sign that we should maybe think about doing it sooner or whether this is actually just normal 16mo behaviour and doesn't mean he's ready.
I'm wondering if it is possible to gradually potty train - e.g. start using a potty initially just in the evenings, then as he gets the idea start asking if he wants to use it during the day but not worrying about it if we are out and about. Or whether that won't work and the whole mad panic for a month going cold turkey on nappies at age 2-3 is better and less confusing.
FWIW we use washables - I heard that the wetness can sometimes make them more aware at a younger age.