If you are educating the child at home: Go to your school district of residence.
If you are attending a private school through ESA:
Per Section 612(a)(10)(A)(i)(II) of IDEA 2004; the district that the private school is located in, should evaluate the student. Please see the following FAQ document from the Ed.gov webpage regarding children with disabilities placed by the parents in private schools (question B-9): http://www2.ed.gov/policy/speced/guid/idea/faq-parent-placed.doc
Question B-9: Which Local Education Agency (LEA) is responsible for ensuring that a reevaluation of each parentally placed private school child with a disability is conducted at least once every three years?
Answer: The LEA where the private elementary school or secondary school is located is responsible for conducting reevaluations of children with disabilities enrolled by their parents in the private elementary schools and secondary schools located within the district.