Dorky thing to say but I'm going to say it :)
Cheers, interested to see what the theme is
So far since July all the jam runners have not been strict or picky and their guidelines always had an 'out' where you don't necessarily follow the jam theme if you don't want to (or like 90% have this provision). Some competitors are strict but the showrunners are always less-strict than that, that I've found. Everybody's pretty welcoming.
When the jam starts tomorrow and the theme is announced, you'll be able to submit your entry. The idea is to wait until the jam begins before starting your song. This way, everyone starts at the same time and works with the theme or guidelines revealed at kickoff. The rules are pretty relaxed when it comes to the theme, but please be fair and don't put others at a disadvantage by starting early. Good luck!