Work on something before the jam starts and post your progress. You don't have to start a new project!
Once Progress Day officially starts, you have a grace period of a couple of days to submit your progress. One day you might come up with that dream game or engine!!
Previous:
https://itch.io/jam/gedg-progress-day-5
https://itch.io/jam/gedg-progress-day-4
https://itch.io/jam/gedg-progress-day-3