Is this a bad question for this SE?
What is the oldest instance of magical familiars being used by witches in fiction, and also called familiars, or a cognate? For example, an English novel having familiars and calling them 'familiars', or a French novel having familiars, and calling then 'familier' (whatever the plural of that is...)
OR is this better suited for History.SE?
OR should I try Google N-grams or something?
The Online Etymology Dictionary has the first use of Familiar to mean a spirit being from 1580s, but that's for things like the Malleus Maleficarum, I think?