This is something I've often pondered but never dedicated any serious research towards. What might jam your findings is that this is exhibition is outside Chinatown, so to speak. There may well have been earlier demonstrations within Chinatown. In fact, that seems very likely. However, that would be near impossible to document as Chinatown gazettes of the time were not preserved to my knowledge (I'm not even sure they existed in America back then). So at this point, you have the earliest documented account that I can think of offhand. Great work. If you hadn't published this online, I might have
bought this for publication.