Huh?
Begotten means sired. The act of impregnating by procreation.
The trinity sired the Son through Marry.
When?
And the angel answered her, “The Holy Spirit will come upon you, and the power of the Most High will overshadow you; therefore the child to be born will be called holy—the Son of God.
Not has eternally been called!
The Christ took upon the human. At THAT point He was to “be called holy - the Son go God”.
Not before.
Never in the OT was the Lord referred to as the Son.
Rather, the Son was prophesied and given the names.
Did not the writer of Hebrews state;
9But we see him who
for a little while was made lower than the angels, namely Jesus, crowned with glory and honor because of the suffering of death, so that by the grace of God he might taste death for everyone.
10For it was fitting that he, for whom and by whom all things exist, in bringing many sons to glory, should make the founder of their salvation perfect through suffering.
11For he who sanctifies and those who are sanctified all have one source.
b That is why he is not ashamed to call them brothers,
...
14Since
therefore the children share in flesh and blood, he himself likewise partook of the same things, that through death he might destroy the one who has the power of death, that is, the devil, 15and deliver all those who through fear of death were subject to lifelong slavery. 16For surely it is not angels that he helps, but he helps the offspring of Abraham.
17Therefore he had to be made like his brothers in every respect, so that he might become a merciful and faithful high priest in the service of God, to make propitiation for the sins of the people.
18For because he himself has suffered when tempted, he is able to help those who are being tempted.
There would be no need for such language had the Son been the Son previous to the conception in Marry.