It works when your kid is ready and thats hard to figure out. Also, there are some other products out there that are similar and use only leg protection. It is really hot for our baby. Like, she sweats so much we think shes over peed her diaper hot. It works most the time for us now, though. The label says it requires air drying...why? Not really magical, but it mostly works now that our daughter is six months old.