Did the dates change? Are they pushing it until next month??
It's in the spirit of things. You can plan and stuff. The honorable is to not work on it before the time. There are pros and cons to it. Most game jams you join will know the theme as it starts but since this is the first time they might drop the theme early to help people plan around the theme.
I think it will be clear who cheats and who doesn't. I think most of everyone wants this to be a normal thing. I have been thinking about hosting my own game jam as a Vtuber but Ironmouse starting this might be a fun trend that will keep happening. If some people do cheat... well we could always make sure they don't come back to ruin other game jams! Either way excited!!!