Elmo Undies

Madelyn is very interested in all things potty lately...She wants to sit on the toilet and wear big girl panties. We found this pacakage of Elmo undies recently and she HAD to have them!! She wants me to put them on over her diaper...I think that we need to start potty training soon (as soon as school is out for the summer!)...YIKES - I will need some advice...