There are a lot of children who are being diagnosed by doctors as having a disability at an early age. Some of those children receive early intervention services, but some do not. If the child does receive early intervention services there are documents that are similar to Individual Education Plans that will make the transition in to the school system easier.
When one does not receive these early intervention services they still made need an Individualized Education Plan, but have no educational documents to follow them. All parents may have is the notes from their medical doctor or psychologist. Medical and education definitions of disability may differ.
Do not panic. This difference in language does not mean that your child will not get the services they need in school. You can start the process easily. Contact the special education department at the school district. Make sure you talk to someone specifically in that department and not just a teacher or principal of the school.
Give them the documents you have from the medical professionals. In writing also give them a detailed letter from you, the parent, listing the diagnoses, your educational concerns, and permission for the school to do their educational evaluations and assessments. According to the education law the school has 60 days to complete this evaluation. However, if there is apparent immediate need or concern express this directly to the special education department and see what things they are willing to put in place immediately. Addressing the big concerns will not only help you and your child, but also the teachers and other school staff.
It is common that parents, especially those who are new to the school system to be nervous. Many have heard that any request will be met with resistance from the school staff. That is not always the case. Approach the staff with a positive attitude and you will likely receive positive results back. When in doubt consult an educational advocate and ask them to help you through the process.