When did the belief that Eden "still exists" originate?

I was reading a (rather sacrilegious) story the other day in which God walks from the location of Eden to the point where the Ark landed, and it got me thinking... Speculation about where Eden might have been is fairly common. However, Scripture says that "the world that then existed was deluged with water and perished" (2 Peter 3:6), and modern Scriptural science believes that the Flood scoured the world so completely that virtually no trace of the old remains, and that any attempt to correlate pre-Flood geography to post-Flood geography is futile. **When is the earliest known reference to the idea that the location of the Garden of Eden corresponds to some existing, post-Flood location?**