I've got two regionals, (at least I think they're regionals?) coming up (Arcade Legends Presents Alpha Attack in early October and Midwest Mayhem on the 27th.) as well.
These will probably mark the first time I use Joker exclusively in a real tournament (Though I managed to get second in a local tournament this week with him so feeling fairly confident), so we'll see how it goes.
Steveo, I know what you mean about getting jittery. Even though I've been attending tournaments for years now, I still get nervous and tend to choke. You just need to find something that helps keep you calm. For me, I usually take a shot or two before starting a tournament. It's not even enough to feel it really, but it keeps me relaxed for my matches.
Another friend uses weed. Yet another just tells himself to calm down in Morgan Freeman's voice (Not even making that up.). Yet another did super fancy stuff in his matches to get the crowd on his side which in turn calmed him down. You just need to find what works for you.