Why Bilbo?

[Formendacil]

Originally Posted by Celuien

True, but I think that it at least dates the genesis of the idea prior to publishing the LotR, making it present during the process of writing The Hobbit rather than an afterthought when The Hobbit became part of the larger Legendarium. Unless, of course, the conversation dates from the same time as the revisions to the riddle game...

No, it goes back to the original edition, I'm pretty sure. And that makes it not only prior to the Lord of the Rings publication, but prior to its very writing. It would have been written, then, before Tolkien ever began the sequel that was to lead to Mt. Doom.