I set up the jam so you can edit anytime before the jam or judging deadline. Judges will be judging on the version that is available when they visit the page, so there is still time for edits during the judging phase.
In a previous jam I was far more rigid about edits but I came to believe it wasn't fair for someone to not be able to fix a simple bug during the long judging period. So, you have a lot of flexibility.