Given this paragraph about Pharaohs, when the title used to address the kings of egypt

Context: The title "Pharaoh" is used for those rulers of Ancient Egypt who ruled after the unification of Upper and Lower Egypt by Narmer during the Early Dynastic Period, approximately 3100 BC. However, the specific title was not used to address the kings of Egypt by their contemporaries until the New Kingdom's 18th Dynasty, c. 1400 BC. Along with the title Pharaoh for later rulers, there was an Ancient Egyptian royal titulary used by Egyptian kings which remained relatively constant during the course of Ancient Egyptian history, initially featuring a Horus name, a Sedge and Bee name and a Two Ladies name, with the additional Golden Horus, nomen and prenomen titles being added successively during later dynasties.

Answer: 1400 BC