The best advice I can give is to forget about your application for a couple weeks. Once you've submitted, you can't take anything back. A lot of people will stress themselves out after they hit submit – everything from second guessing their responses to the questions to wondering if they remembered all of the punctuation, checked the spelling, and used proper nomenclature in each answer. All that does is causes you more stress. Even if you did make a mistake, you can't fix it, so just let it go and whatever happens, you'll know by early October either way. Like Walt said, "Why worry? If you've done the very best you can, worrying won't make it any better."
This is my second year applying. I applied in 2014 (for the 2015 panel) and made it to the second round. I didn't apply last year because I couldn't make it for the training dates. After I hit submit on my last application in '14, I just went back to my normal daily routine. I tried to not even think about the DPMP or the process at all, and was pleasantly surprised when I received an email in mid October telling me that I had made it to round 2 and giving me instructions from there. Only then did I focus on it again. After I submitted that round, I watched Twitter and Facebook like a hawk, searching for information about when we'd hear anything for round 3. I started to stress myself out, and was really let down when I didn't advance to round 3. This year, I'm just going to submit my best and move on. If I continue through the rounds, great! If not, I'll try again next year. There are some that have applied every year (and this is the 10th year.)