I know that we're allowed to add code scripts to our libraries beforehand, but are we allowed to work on concept art ahead of time if we've got an idea for what we want to make (as long as we're not creating actual in-game art assets)?  Would pre-planned design docs be allowed, or do those need to wait until the jam starts as well?

Basically, I've got a couple ideas kicking around in my head and, since I'm really new to development (and have never joined a game jam before), I'm wondering just how much conceptualizing I can/should do before things kick off.

To me the fun of a gamejam is in the lack of preparation. If you know what you gonna do what stops you from doing it now? Being creative about a certain theme is like 75% of the fun of gamejams to me...

But technically i dont think concept art is not allowed - so youre free to go (even though i recommend no prep at all).

To me it's like an open-book exam. You're not allowed to look at the answers beforehand but you can bring notes with you into it.

Basically, don't create anything you intend to put in your game. Setting up reference material and doing practice runs would be helpful. I'm not running the jam so I'm not 100% it's allowed, but that's my view on it.

But always be aware that the theme could potentially throw all your ideas away, and that the addition of the theme could give you better ideas than what you came up with before knowing it.

That's a good point, I hadn't considered that the theme might change things up from what I had in my head. I think I'll practice some other ideas in the meantime, but try to keep the slate blank until I know what the theme is. 

Thanks for the replies!