I never potty trained my first child untill he was 2 and a half I didnt see the point in trying untill he was properly ready and he had better understanding. When we did get round to doing it, it went well and he picked it up quickly. Lucas, I did around his 2nd birthday he was much more independant so it made it easier. Although bear in mind they do say girls are easier than boys to train.
I am going to do the same with Alfie when he hits 2 we will try with him. I have had a potty in the house for the last couple of months and we dont really do much with it but I like to have it about and when he picks it up I tell him what its for. He doesnt really understand at the minute but by the time he is ready he will be more than used to seeing the potty around and it shouldnt be such an issue. My health visitor told me that babies dont really know when they need to go much before 18mths, some babies may be trained before this but thats more to do with the parents sitting them down to go rather than them doing this by there own.
On the subject of training pants, some may disagree but I think unless you are going out somewhere for the day they are a waste of money! You get less in the pack than nappies although they are the same price and sometimes more expensive. Also I tried using them for my first son and got nowhere. When I spoke to my health visitor she said not to use them because when the child wee's the training pants they soak it all up so they dont know what they have done, where as, if they are in normal pants they will be wet and begin to realise that isnt such a nice experience! (Just to cover myself... Not that I left my children in thier wet undies, I always changed them straight away)
This is just my experience and advice I was given! I hope I havent gone on too much and hope it helps!!