I would’ve thought, based admittedly on nothing but the fact that people have been baking with yeast for millennia, that it was far older.
Yes, that was my assumption also. And it still may be, because bread-making was for millennia so universal an activity that hardly anybody felt a need to write down how it was done. (I don’t believe that a single recipe for plain ordinary bread exists in any of the English-language cookery books printed before the 19th century; people whose business it was to make bread knew as a matter of course how to make it, and they had learned directly from other people who knew how to make it, not from a recipe. Only recipes for speciality breads and buns that not every cook or housewife was expected to know merited publication.)
I have flipped through my collection of facsimile 18th-century cookery books, and the instructions for making dough for such things as Wiggs, Yeast Cakes, and French Role mostly use some such phrase as ‘Let it stand/lie to rise’. It could be, I suppose, that the word proving was a term of art among professional bakers, not used by domestic cooks.