In one sense, Yeshua/Jesus is already the King; on the other hand, He must return to sit on His throne in Jerusalem as the heir to David over the whole house of Israel.  The invisible in the heavenlies must become visible on the Earth, and throughout the created Universe.  Meanwhile, He has received all authority in heaven and on Earth.  He is already chosen, appointed, and anointed by the Father to reign over all things (other than the Father Himself); and He is waiting for the Father’s appointed time to return to Earth and restore YHVH God’s Kingdom to Israel, and openly over the Gentile nations.  At the end of the 1000 years Kingdom, Yeshua will deliver the Kingdom [of God] to God the Father, when He puts an end to all rule and authority and power:  love and righteousness will be perfected, and God will be all in all.

This is my current understanding.