Every time the inspired Scriptures speak of the pre-human life of Jesus, they declare that he was "at God's side" not inside his mind. In fact, Jesus prayed to his Father saying:
John 17:5 So now, Father, glorify me at your side with the glory that I had alongside you before the world was.
The original wording is:
καὶ νῦν δόξασόν με σύ, πάτερ, __ So now glorify me, you, Father,
παρὰ σεαυτῷ __ at your side
τῇ δόξῃ ᾗ εἶχον __ with the glory that I had
πρὸ τοῦ τὸν κόσμον εἶναι __ before the world was
παρὰ σοί. __ alongside you.
Jesus clearly and very well remembers the glory he had when he was at the Father's side and that's why he asks to be granted again.
About John 8:56-58:
John 8:
56
"Abraham YOUR father rejoiced greatly in the prospect of seeing my day, and he saw it and rejoiced.”
57 Therefore the Jews said to him:
“You are not yet fifty years old, and still you have seen Abraham?”
58 Jesus said to them:
“Most truly I say to YOU, Before Abraham came into existence, I have been.”
The original Greek wording is:
πρὶν __ Before
Ἀβραὰμ γενέσθαι __ Abraham came to exist
ἐγὼ εἰμί. __ I am
An easy to understand translation of that would be:
I DO EXIST SINCE BEFORE ABRAHAM WAS BORN.
Here I quote 4 passages showing Jesus coming from heaven,
changing form to flesh:
John 1:14 So
the Word became flesh and resided among us, and we had a view of his glory, a glory such as belongs to an only-begotten son from a father; and he was full of divine favor and truth.
Phil. 2:7 No, but
he emptied himself and took a slave’s form and became human.
1 Tim. 3:16 Indeed, the sacred secret of this godly devotion is admittedly great: ‘
He was made manifest in flesh, was declared righteous in spirit, appeared to angels, was preached about among nations, was believed upon in the world, was received up in glory.’
Heb. 2:14 Therefore, since the “young children” are sharers of blood and flesh,
he also similarly shared in the same things, so that through his death he might bring to nothing the one having the means to cause death, that is, the Devil.