Psalm 110:1 “YAHWEH (the Divine Name appears) said to my Lord (adon means a human lord), sit at my right hand until I make your enemies the footstool of your feet.”
The text does not say, “Yahweh said to my Yahweh,” nor “Yahweh said to my Adonai (which would mean Yahweh said to God). Here we have One Yahweh Person who spoke to one human son person rather than two co-equal Yahweh Persons.
If Jesus had eternally existed as an alleged God the Son beside the Father throughout eternity past, then why did the Father say to the son, "sit at my right hand" if he was already at the Father's right hand?