Switching to cloth diapers at 15 mos helped. Also, having an older sibling who was potty trained, and a few good potty videos and books, and allowing my daughter to see me go potty. We used potty chair, then stool to reach big potty. The big toilet potty seat cover was too unstable for my kids, especially my developmentally delayed son.
12/2/13 at 5:49pm