Arrianus’ knowledge of the nomen sacrum notation [in Letter from Christian Arrianus to his brother Paulus, dated to the 230s CE. Ed.pr. P.Bas. I.16; new edition: P. Bas. 2.43.] can only be attributed to an independent reading of Holy Scriptures. The earliest examples with nomina sacra contractions are found in Christian literary papyri such as copies of the Gospel of John, which are dated tentatively to the late second century. Our author must therefore have had these Gospels to hand and read them, as just having heard them would not have imparted knowledge of the abbreviations.

Sabine R. Huebner, Papyri and the Social World of the New Testament, 22.