Try to plan ahead! This doesn't have to be an elaborate plan but just list everything for each day (day 1: set up + brainstorm, day 2: base mechanics finished ... day 7: builds + itch page). This is my first game jam and it helped tremendously. I also submitted the game like 16 hours before the deadline, which was possible because of my planning. This avoided the itch crashes. P.S.: If you have more than 24 hours of bug-fixing to do after building your game, it's very unlucky and no one could solve it... Good luck finishing your game!