While reading William Bridge's, "The Wounded Conscience Cured," (1642) I came across Bridge's usage of the term "New Testament" :
"And in the New Testament, Romans 13.1..."
-William Bridge, "The Wounded Conscience Cured," (5)
While obviously not the earliest usage of the term "New Testament," this did get me wondering about how early on the term first came into usage.
David Trobisch, a prominient scholar on the formation of the Christian Bible, records in his book what he deems to be the earliest usage of the term in an anonymous late second-century treatise against the heresy of Montanism :
"At approximately the same time, (late second century) the previously mentioned anonymous treatise against the Montanist movement seems to use the term New Testament in reference to a written source. The author explains that he was initially very reluctant to write at all. He did not want to create 'the impression that he was adding anything to the word of the gospel of the New Testament; since no one, who decided to live according to the gospel, can add to it or take away from it.'"
-David Trobisch, "The First Edition of the New Testament", (44)
With regards to answers, "New Testament" does not have to be used in reference to a modern day canon; however, "New Testament" should inherently be used to describe some sort of canon from antiquity.
I am curious if there are any other earlier usages of the term "New Testament" or is David Trobisch's example truly the earliest, extant usage of the term?
Just to clarify, I am not inquiring of the earliest English usage of the term, but earliest in any language, so a usage resembling (but not exclusive to): Novum Testamentum, Καινή Διαθήκη, ܕܝܲܐܬܝܼܩܝܼ ܚܵܕܬܵܐ.