How and when is the random prosperday decided? Obviously the next one is already somehow chosen, or we would not see a countdown for it? I think it'd be more interesting if we did not know in advance at all. Every day could be a prosperday, and one would not know until the rewards start to grow. This would cause a rush of interest when miners adapt and the words spread around.
I do not know but an interesting question i will ask IN Mean when he gets back from his business trip on Friday