I went through the same thing with my little one. I don't think it is ever too early to get them on the right path as far as the 'function' of the whole process. I certainly found it helpful to have my oldest help with the youngest, considering the younger sibling usually copies everything the oldest does. I had my little man using public bathrooms in a few months... even in a <a rel="follow" href="http://www.mesawasteservices.com/providers-Denver-CO.html... potty rental denver</a>.
Hope everything worked out for you.