The scripture referred to in this question is Mark 13:32 (NASV) which states “But of that day or hour no one knows, not even the angels in heaven, nor the Son, but the Father alone.” At the time these words were uttered during Jesus’ first advent, Jesus did not know when he would be coming again. He needed to die on the cross first, and ascend to Heaven. Then the scroll was given into his hands to be opened. Revelation 5:12,“Worthy is the Lamb that was slain, to receive power, and riches, and wisdom, and strength, and honor, and glory, and blessing”. Revelation 6 goes on to talk about the scroll being opened. As Jesus opens the scroll, more and more of His Father’s divine plan is revealed to him, until he is fully informed as to the plan and the timing. To suggest that Jesus would never know the time that he was coming again or meeting up with His Bride, the Church, would be absurd, because as we all know, weddings take much time for the preparation. God would certainly give him a “heads up” as to when this would take place.
The scripture that tells us that Jesus doesn’t know the time or hour that God will send him is another good argument against the idea that God, Jesus, and the Holy Spirit are one being in 3 different parts.