How early are you imagining the gospels were written Neon?
Most conservative scholars would date Mark to the 50s, which would have been the time that Paul was writing his epistles. Luke and Matthew came a bit later, with John bringing up the rear, probably toward the end of the first century. I realize that some of Paul's letters may have pre-dated the Gospels, but the story contained in the Gospels would have been well known within the Christian church even before they were written. Paul quotes creeds in his letters that are thought to pre-date any writings of the NT, but that still carry a high Christology. My point is not really whether the Gospels were in existence at the time of Paul's writing anyway, but that his lack of mention of them can't be used as an argument that he was ignorant of them. That's an argument from silence, and is easily explained by the fact that his purpose in writing was not to recount the Gospel stories, but to expound on the theological implications of the coming and work of the Messiah.
I might add that I am not impressed by arguments for loate dating of the Gospels, based on the idea that Jesus predicted the destruction of Jerusalem, and therefore the Gospels had to have been written after that event. The presumption is that there can be no such thing as actual prophecy, therefore Jesus could not have known what would happen 40 or so years later. This argument merely begs the question, since the premise of the Gospels is that Jesus was the Messiah sent from God who could prophesy accurately and work miracles.