On his blog Brice C. Jones has written about his discovery of an unpublished Sahidic Coptic fragment of John and his upcoming published presentation of the find in New Testament Studies next spring (April 2014). According to his post, this fragment is the earliest known all Coptic manuscript containing commentary on the Gospel text delineated by the heading “hermeneia” (“interpretation” or “explanation”). He does not mention the possible dating of the fragment, however. According to Jones, other Coptic manuscripts containing hermeneia segments are bilingual, with a mixture of Coptic and Greek.
Congrats on a great find!