Let us look at the meaning of the verse which you continue to cite:
"Therefore being a prophet, and knowing that God had sworn with an oath to him, that of the fruit of his loins, according to the flesh, he would raise up Christ to sit on his throne" (Acts 2:30).
Here Peter is speaking of the fact that Christ would sit upon the throne of David. You say that has already happened. Here is what we read about the Lord Jesus and that throne:
"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: And he shall reign over the house of Jacob for ever; and of his kingdom there shall be no end" (Lk.1:33).
If you are right then now the Lord Jesus is sitting upon His own throne, the throne which was given to Him and Him alone. However, He is now sitting at His Father's throne and not His own throne:
"To him that overcometh will I grant to sit with Me in My throne, even as I also overcame, and am set down with My Father in His throne" (Rev.3:21).
Are you so spiritually deficient that you cannot even distinguish between the throne of the Lord Jesus (the throne of David) and the throne of the Father? I guess that you are.
Notice that I am the one who is interpreting these texts which I quoted from the NT according to their normal meaning. It is you who is doing your best to pervert that plain meaning.