Three is a big birthday for children with special needs. With that milestone comes a transfer of therapy responsibilities from Early Intervention providers to your local school district. While your EI provider may be able to give you information on what to do, and help smooth the transition, you will need to be proactive and contact your school district well in advance of that age marker.
At least three months before your child hits the big 0-3, contact your school district's special education department and ask about services for three-year-olds. Explain that your child has been in Early Intervention. You will have to go through an evaluation by the school district's child study team to determine your child's eligibility for special-education preschool, and that can take several months. Since EI services will end whether your child's Pre-K placement is ready or not, you'll want to try to prevent a lengthy break.
The evaluations should be fun for your child. The results may be traumatic for you. It's never easy to hear that your child is delayed and needs services, or to get a big fat report on just how much help is needed. But preschool should be a great opportunity for your child to both get therapy and socialize.
What that special-education preschool experience looks like for three-year-olds will vary by district, and it's worth asking to take a look at the sort of classroom your child will be in. The setting will most likely be self-contained, and the school day a short one. Busing should be available; you may want to make sure that the plan for your child includes a car seat being provided, especially if your little one has low muscle tone.
There are special-education preschool classes for three-year-olds and four-year-olds, and after that a decision will have to be made on whether to formally classify your child for special education, and what sort of kindergarten class will be appropriate. Right now, though, at age three, any labels applied in the evaluation process don't stick. Many kids go through special-education preschool and wind up going on into regular education. Take this opportunity to give your child some extra help and support in these very young formative years, and see where you're at when it's over.