The oldest actual texts we have date from at least a century or two after Jesus. We do not have originals. The earliest versions we have are not originals and almost certainly have been altered from what the authors originally wrote. And there are many revisions subsequent to those versions.
And the dates in which the books were originally written appear to be no earlier than at least 70-90 AD.
“The oldest actual texts we have date from at least a century or two after Jesus”
The oldest actual text would be a fragment from John from chapter 18 found in Egypt, dated between 125-160AD. Though, it was mentioned by Papias about 100AD, so obviously it would have to be even older than that. John was likely written about 80-90AD, by John himself who was then living. Irenaeus, born around 120AD, quotes from John here:
“Now the Gospels, in which Christ is enthroned, are like these. For that according to John expounds his princely and mighty and glorious birth from the Father, saying, ‘In the beginning was the Word, and the Word was with God, and the Word was God,’ and, ‘All things were made by him, and without him nothing was nothing made’ . Therefore this Gospel is deserving of all confidence, for such indeed is his person.” (Against Heresies, 3.11.8)
(Actually he quotes from all 4 Gospels more than 600 times.)
“The earliest versions we have are not originals and almost certainly have been altered from what the authors originally wrote.”
“Almost” certain. Which basically means that you’re not certain at all. Good for you!