This is not Biblically true.
Do you understand hermeneutics.
Especially the historical context?
I understand your teacher is the doctrine of the trinity.
The Lord (God of all) said to MY Lord (Davids Sovereign)
Jesus's God has set Him above His companions. If Jesus were coeternal, He would already be above all because He is God. Rather than inheriting all things from His God and Father and receiving authority.
Its not to us there is but one God the Father, Son and Spirit from and through all things come.
yet for us there is but one God, the Father, from whom all things came and for whom we live; and there is but one Lord, Jesus Christ, through whom all things came and through whom we live.
It not this is eternal life that they know us the only true God.
Now this is eternal life: that they know
you, the only true God, and Jesus Christ, whom you have sent.
In the Son lives all the fullness. In that oneness with the Father He is all that the Father is (God) But His spirit is not Deity and is Gods firstborn and has always been the Son. Not God in that context. A promised Son who will be called God. A Son who has the Fathers nature but is not the Father. He and the Father are one and He is not a God as some might state He is the First and Last.
Because He is a Son the writer of Hebrews took pain to contrast His Sonship with the angels of God to show the superiority of His Sonship. Hebrews 1 is about the Son not about God.
He is Gods Firstborn and has always been the Son
The beginning of the creation of God and the Firstborn of all creation -His spirit -the fullness was gifted.