As per this picture, posted by director Larry Teng, the one episode that will be produced before the hiatus but will be a part of NCISLA Season Five will be called “Unwritten Rule” and was written by Joseph C. Wilson & Jordana Lewis Jaffe.
Filming starts April 24th… so with a filming duration of 8 days per episode the cast & crew should have their well-deserved hiatus after May 3rd.