'Once' in the Bible

Go at once to King David and say to him, ‘Have you not, my lord, O king, sworn to your maidservant, saying, “Surely Solomon your son shall be king after me, and he shall sit on my throne”? Why then has Adonijah become king?’

For the king had at sea the ships of Tarshish with the ships of Hiram; once every three years the ships of Tarshish came bringing gold and silver, ivory and apes and peacocks.