Beginning with the school year 1999-2000, any person prior to permanent appointment as a principal for any elementary school, secondary school, or vocational center must be assessed for instructional leadership and management capabilities by the Leadership Academy of the South Carolina Department of Education. Districts may appoint such persons on an interim basis until such time as the assessment is completed. A report of this assessment must be forwarded to the district superintendent and board of trustees. The provisions of this section do not apply to any persons currently employed as principals on the effective date of the provisions of this paragraph nor to any persons hired as principals before the beginning of school year 1999-2000.