The Spirit (God the Word) did in fact preexist from all eternity the same as the Spirit (the Father) and the Spirit (the Holy Spirit) did.

The Son (the man Jesus) did not exist before the Father created this body and the Holy Spirit placed the holy embryo in the womb of the virgin Mary.

Hebrews 10:5 (AV)

5 Wherefore when he cometh into the world, he saith, Sacrifice and offering thou wouldest not, but a body hast thou prepared me:


Hebrews 1:5 (AV)
5 For unto which of the angels said he at any time, Thou art my Son, this day have I begotten thee? And again, I will be to him a Father, and he shall be to me a Son?

This day, will be, shall be indicative of a time when these were not true or did not exist yet.