That is why I presented six verses that attest to David being King again and then asked for a timeline.
I understand why you asked for a timeline, but there is nothing in scripture which truly attests to David being King again. Instead, it is the son of David, who will sit upon the throne of David, to whom the kingdom will ultimately be given.
Isa 9:6
For unto us a child is born, unto us a son is given: and the government shall be upon his shoulder: and his name shall be called Wonderful, Counsellor, The mighty God, The everlasting Father, The Prince of Peace.
Isa 9:7
Of the increase of
his government and peace
there shall be no end, upon the throne of David, and upon his kingdom, to order it, and to establish it with judgment and with justice from henceforth even for ever. The zeal of the LORD of hosts will perform this.
Luk 1:30
And the angel said unto her, Fear not, Mary: for thou hast found favour with God.
Luk 1:31
And, behold, thou shalt conceive in thy womb, and bring forth a son, and shalt call his name JESUS.
Luk 1:32
He shall be great, and shall be called the Son of the Highest: and the Lord God shall give unto him the throne of his father David:
Luk 1:33
And he shall reign over the house of Jacob for ever; and of his kingdom there shall be no end.