Was just curious and for fun. If Mods are not able to extract that data, I wondered if the sellers were happy to contribute Anything below the hour mark...step forward.
I know I bought my Speedy from @Drawarms in under an hour. Just checked... 52 minutes flat. I really wanted it. https://omegaforums.net/threads/1974-omega-speedmaster.51844/#post-627601
I don't know how it ranks on the list but my fastest sale was just over an hour from posting to acceptance and it was collected that evening: https://omegaforums.net/threads/sold-smiths-de-luxe-1951-1952.59445/
I've seen a couple quick ones, bought one, and sold a fast one myself. I think they were all done in under an hour.
I know of a couple. I sold an A386 and a Watchco SM300 in way less than an hour (that's when you realize "shit, I priced it too low")
There was that Girard Perregaux "Calatrava," that went in about 15 minutes and sparked a frenzy of comments, a Seamaster of mine went in about 30-45minutes and there was a GP Polerouter that got done "with pictures being sent to the buyer as the upload function wasn't working..."