I wish I had some experience to help you but I'm also working on my first 'show' quilt. I am not expecting to be accepted into the show, but just the fun of working on a quilt for a show and sending in for judging is my only experience so far.
I am not working on a quilt nearly as beautiful as yours, but the piecing is still a challenge, because of that lingering idea that it's going to be judged.
I would follow Paper's advice especially about using the point of your ripper on one side and the other etc so you don't stretch the pieces your unsewing.
My challenge is that my quilt is a QAYG which I've never done before. Still have 3 months before submission and it's a wall quilt so I'm taking my time and studying the directions and the technique and I won't work on it if I'm the least bit tired or stressed. I want it to be a fun experience. I will admit it is intimidating to know that someone else is judging my work, but what's the worst they can say... No. But I will love it, because I love the design and the fabric, so I say....do your best and enjoy the process.
Stitch124