I wrote a game that is very trashy last month, so unfortunately early - is it acceptable to submit games we have already written if we have never uploaded them to itch? Or would you rather we just used the trash tag when we upload it to help popularise it?

So long as it fits in with the theme and complies with the jam rules, I don't have any issues with submission of existing games. Go for it!

Excellent, thank you! :)