By the question it is assumed you are referring to the transition from home or Infant community into a Primary (2.5-6+) environment.  Bathroom independence is often hampered by the prolonged use of paper diapers and pull-ups.  A child can become toileting independent by the time they are walking well, around 15-18 months. Once they join a primary environment, they will observe the other children using the toilet independently. The adults need to give “toileting” to the child:  to go when they need to, to clean up themselves (unless there is a bowel movement and they need help), to change their wet pants, put the wet ones in a bag to take home, washing their hands, etc.  Most children by the age of 2.5 have the absolute possibility of being bathroom independent if supported, physically, environmentally and emotionally, and after an adjustment period of a couple of weeks into the new environment, will begin to manage themselves. There must never be a negative response from any of the adults—staff or parents—so that toileting does not become a power issue.