When will the prompt be revealed? I know that Wednesday the 18th is given on the jam page, but that would be some six days into the jam so I assume that date is wrong.

The prompt will be released on Wednesday. The page is up but the actual jam doesn't start until Thursday the 19th

I will usually launch the page up a few days early so people can join before it starts.

So after looking over it about 3 times I finally see the error (ha) and it has been fixed. Due to the circumstances, the jam will now start on the 19th and end the 26th so people have a chance to join. Sorry for the inconvenience everyone.