I know 1993 prototype has been dumped and released but from my understanding that was the only one has been dumped so far?
While going through my old stuff I found this Panorama Cotton prototype cartridge dating 17 May 1994.
Given the Japanese release date this would put this build around 4-5 months before launching.
Haven't had time to play test whether there are obvious difference yet - I still need to find my copy of Panorama Cotton to compare.
When I do I will post the video to my Youtube channel.