Today is day one of toilet training my 19 1/2 month old son. Despite having read "Toilet Training w/o Tantrums" I'm confused. Some of the answers to questions here contradict the book regarding the use of diapers. What is the most effective approach for nap and bed times? Diapers or underwear? I understood from the book that once training beings, diapers are gone, period. Please advise.