Not true. The Son had been prophesied many times in the OT.
Psalm 2:7 “I will surely tell of the decree of the LORD: He said to Me, ‘Thou art My Son,Today I have begotten Thee.
Psalm 2:11-12 "Serve the LORD with fear, And rejoice with trembling. 12 Kiss the Son, lest He be angry, And you perish in the way, When His wrath is kindled but a little. Blessed are all those who put their trust in Him."
Proverbs 30:4 "Who has ascended into heaven and descended?Who has gathered the wind in His fists?Who has wrapped the waters in His garment?Who has established all the ends of the earth?
What is His name or His son’s name?
Surely you know!"
Isaiah 7:14 “Therefore the Lord Himself will give you a sign: Behold, a virgin will be with child and bear a son, and she will call His name Immanuel."
Isaiah 9:6-7 "For a child will be born to us, a son will be given to us; And the government will rest on His shoulders; And His name will be called Wonderful Counselor, Mighty God, Eternal Father, Prince of Peace. 7 There will be no end to the increase of His government or of peace, On the throne of David and over his kingdom, To establish it and to uphold it with justice and righteousness From then on and forevermore. The zeal of the LORD of hosts will accomplish this."
Daniel 3:25
"He answered and said, Lo, I see four men loose, walking in the midst of the fire, and they have no hurt; and the form of the fourth is like the Son of God."