How is it not David's throne?
He was anointed king of Israel by God on the holy mount when the kingdom of God came in power and the two olive trees who stand before the lord of the earth were there standing with him.
And he said unto them, Verily I say unto you, That there be some of them that stand here, which shall not taste of death, till they have seen the kingdom of God come with power. And after six days Jesus taketh with him Peter, and James, and John, and leadeth them up into an high mountain apart by themselves: and he was transfigured before them. And his raiment became shining, exceeding white as snow; so as no fuller on earth can white them. And there appeared unto them Elijah with Moses: and they were talking with Jesus. Mark 9:1-4
Then his disciples welcomed the king of Israel to Jerusalem.
Took branches of palm trees, and went forth to meet him, and cried, Hosanna: Blessed is the King of Israel that cometh in the name of the Lord. John 12:13
It says that Christ went to heaven to receive the kingdom because natural Israel rebelled and refused to be ruled by the heir to the throne of David.
He said therefore, A certain nobleman went into a far country to receive for himself a kingdom, and to return. Luke 19:12
But his citizens hated him, and sent a message after him, saying, We will not have this man to reign over us. And it came to pass, that when he was returned, having received the kingdom, then he commanded these servants to be called unto him, to whom he had given the money, that he might know how much every man had gained by trading. Luke 19:14-15