DD started young, i bought a potty just for her to get used to it, took her ages to actually do a wee in it, and even then it was only once. We moved to the big toilet with one of those little seats on it and now she pretty much asks to go ever time in the toilet. although im not brave enough to get rid of the nappy! I guess we started around 14 months, but she only really got it at about 17 months, and even then we have weeks were she isnt keen and weeks where she is totally on the ball! I just decided that it didnt matter if she TT or not and i think being super relaxed about it really helped!!