The question I asked here seems to be like a NP-hard problem in that a single example would answer the question with a "yes" but a "no" would require an exhaustive search of all Christian thought (presumably including works no longer extant!). I do not think it is worthy of being closed--it is potentially answerable--, but I suspect the answer may be "no" in which case a referenced answer would not be possible.
I am tempted to suggest that someone provide an answer along the lines of "It appears likely that there was no earlier use" (I need to clarify the question and skim through Confessions to find a reference--as well as probably comment on answers, though mostly through clarifying the question.), so that I could accept an answer (but I am a little hesitant to accept a "probably no").
Anyway, this issue seems more general than just that single question.
My asking this question here was motivated by the question about closing open-ended questions.