It depends on the district too. Some are more apt to outplace than others. I work with children with severe special needs and have seen Salem, for example, not hesitate to send kids out immediately (like at their initial IEP meeting prior to their 3rd birthday) because the magnitude of their needs was too great. There are also families of means who move to certain towns specifically because that town is known as more likely to outplace their child without a fight. Newton is a town that has that reputation within the local pediatric circle.