What is the earliest documented usage of the term "Sola Scriptura"?

While the concept may have existed far prior, a recent discussion has left me wondering - What is the earliest documented usage of the term "Sola Scriptura" in Christian writings. I am not interested in articulation of the concept, but instead of the first documented usage of this specific and actual phrase in reference to the doctrine (not just coincidental usage) - so please be sure to include a quote in your answer.