Potty training - When I am big

So my daughter is now 3 and says when she is "big" she will go potty on the big girl potty. I have read all the books, articles, web sites and found nothing that would fix this, "when I am big" problem. I even asked the doctor, no help there. He just told me to have her change her own diaper! Right, I am going to let a 3 year old change her own poopie diaper!

So one day, I woke up and was done with the diapers, with the "when I am big" attitude and put my little girl in panties and told her every 30 minutes we are going to go potty. Well, it went great....then she went outside to play and came in crying because she had an accident.

Several weeks have now passed and she is potty trained. She has very few accidents and she is usually more upset then I am. I guess I was the one that had to show her who was really the big one in the house. LOL