In 2 and a bit weeks I'll be participating in a hackathon, where I'll create the prototype of an application that I want to base a company off of in the maybe-near future.
Both the prototype and the real version (made under the company) will be entirely open source.
I'm not concerned about people copying me or starting a similar company as me or what not. I just want to work on my product in peace.
What I am scared of, however, is a case where a mean party first copies it from me and later tries to sue me as breaching their rights/copying them, because they got legal documents X, Y and Z prepared but I didn't.
I don't really know anything about law, but basically I want to know how I can protect my company, not my code.
Also, is there any special preparation I need to do before the hackathon, considering that the company that I want to run the real version of this product in the maybe-near future doesn't exist yet? (i.e. what if after the hackathon but before I start my company, some other party starts a company with the same idea - how can I also be protected in that case?)
In probably-idiotic-non-legal-terms, how can I set myself up such that, legally speaking, it's obvious that "I came first" (unless somebody did actually precede me) and that I can use that fact to defend myself if under lawsuit from a copy-cat?
PS: The company will be based in Australia, but its services are all online (international).