There's no rules about anything. The only officially-sanctioned contest is the Bowhunting contest, but as long as either Mods or some generous soul agrees to run the other contests they are more than welcome too. Feel free to sign up for as many of them as you wish, it doesn't matter much to us. The more the merrier.

As for the official sign-ups for this year's bowhunting contest, I believe they usually start sometime around the 1st of August, and wrap up about the 1st of September. That way we're ready to rock for the seasons that open early. Be patient guys, we'll get there soon enough.