With the exception of certain Old Covenant prophecies Yeshua, before his birth as a human being, was not called the Father's SON:

II Samuel 7:14 - I will be a father for him, and he will be a son for me. IF he does something wrong, I will punish him with a rod and blows, just as everyone gets punished;

Psalm 2:7 - "I will proclaim the decree" Adonai said to me, 'You are my son; today I became your father...

YHWH God was not referred to as the Father before then. The Father's existence was not even fully understood until after the Messiah came:

Matt. 11:27 - "My Father has handed over everything to me. Indeed, no one fully knows the Son except the Father, and no one fully knows the Father except the Son and those to whom the Son wishes to reveal him.

Luke 10:22 - "My Father has handed over everything to me. Indeed, no one fully knows who the Son is except the Father, and who the Father is except the Son and those to whom the Spm wishes to reveal him.

It was not until Messiah's birth to a human mother that He was given the title "Son of Man." It was necessary for Yeshua to remind Himself of His glory so that He could become the sacrifice for our sins so that He (our High Priest) could fully understand our weaknesses and trials as human beings:

Hebrews 4:15 - For we do not have a cohen gadol (high priest) unable to empathize with our weaknesses; since in every respect he was tempted just as we are, the only difference being that he did not sin.

This entire scenario was part of God's Master Plan of salvation for mankind. Among the man titles by which Yeshua was known in the Old Covenant, "Son of Man" reveals one of Messiah's many important characteristics.

Daniel 7: 9 I beheld till thrones were placed, and one that was ancient of days did sit: his raiment was as white snow, and the hair of his head like pure wool; his throne was fiery flames, and the wheels thereof burning fire. 10 A fiery stream issued and came forth from before him; thousand thousands ministered unto him, and ten thousand times ten thousand stood before him; the judgment was set, and the books were opened. 11 I beheld at that time because of the voice of the great words which the horn spoke, I beheld even till the beast was slain, and its body destroyed, and it was given to be burned with fire. 12 And as for the rest of the beasts, their dominion was taken away; yet their lives were prolonged for a season and a time. 13 I saw in the night visions, and, behold, there came with the clouds of heaven one like unto a son of man, and he came even to the Ancient of days, and he was brought near before Him. 14 And there was given him dominion, and glory, and a kingdom, that all the peoples, nations, and languages should serve him; his dominion is an everlasting dominion, which shall not pass away, and his kingdom that which shall not be destroyed.