I was thinking about the phrase 'young padawan,' and it seemed to me to be a permanent part of Star Wars lore. Yet, I definitely remember being into Star Wars well before the prequels, while I just re-watched the original trilogy and don't remember hearing the term padawan anywhere. There are multiple uses of the word 'apprentice;' but in movie terms, padawan seems to be fist introduced in Episode I.
In the greater Star Wars universe and all its associated products, what is the first use of the word 'padawan'? To be clear, I don't care about what is canon and what is not, I want to know the first time it showed up in any written script, book, video game, etc.