A few verses later John calls Jesus the word. So no, if we only had John 1:1, we would be stuck wondering. He also says Jesus is the light first spoken of - the light spoken of before the Sun is made.
Verse 14 says, 14The Word became flesh and made his dwelling among us. We have seen his glory, the glory of the one and only Son, who came from the Father, full of grace and truth.
So reading comprehension tells us that Jesus is the word.
1In the beginning was the Word, and the Word was with God, and the Word was God. 14The Word became flesh and made his dwelling among us. We have seen his glory, the glory of the one and only Son, who came from the Father, full of grace and truth.
“In the beginning was that Word, and that Word was with God, and that Word was God. This same was in the beginning with God. All things were made by it, and without it was made nothing that was made. In it was life, and that life was the light of men. And that light shineth in the wilderness, and the darkness comprehendeth it not.”
(John 1:1-5, Geneva Bible)
“And the Word was made flesh, and dwelt among us, (and we saw the glory thereof, as the glory of the only begotten Son of the Father) full of grace and truth.”
(John 1:14, Geneva Bible)
Jesus is the incarnation, the enfleshment, of the word.
When does reading comprehension tell us that “Jesus is the word”?
Are you reading it back into the prologue?
I’m not. I harmonize it with the birth narratives in Matthew 1 and Luke 1.