The agency I worked for in Alberta (Calgary) was allowed to put me over if they felt I was able to handle it. Because of my teaching background and experience I often got the child whose caregiver was sick. I was also often over in age ratio with more than 2 under two - ie those times when the one child I had would be 2 in a couple months and would be an under 3 at that point.

Mind you this was back years ago before regulations became the be all and end all rather than strong suggestions.