The only scriptures were the OLD TESTAMENT..
To echo what Half banana said above:
Why not The Book of Jubilees? Or The Assumption of Moses, which is a likely source for Jude 1:9?
How about The Book of Enoch or the Book of Jasher or The Epistle to the Laodiceans or The Life of Adam and Eve, or The Martyrdom of Isaiah or Paul's original letter to the Corinthians. (Referenced in 1 Corinthians)
The point is that we have no way of knowing what writings the early Christians considered authoritative. All the writings I mentioned above are either quoted or referenced in what we call the New Testament today.