Just relax, you'll be fine. Almost everyone is kind of nervous the first time they carry. Its natural for you to feel like you're doing something wrong because of the way people act towards guns these days. The biggest thing is to stay calm, don't play with your holster or gun while out in public (don't play with gun at all), and try not to even pay attention to the fact that you're carrying. Don't worry about looking fidgety, as if you worry about that to much, you will be fidgety.
For the first week if you really feel like you'll be that nervous, don't have a round chambered. I even know of two guys who carried the first week with no mag just to get used to carrying and get over the first time jitters.
Starting off by carrying at home and while going to local stores for short shopping trips is also another way to help you out if need be. But most of all, you have everyone here that will be your support if need be. Most of us have been in the new to carrying shoes, so we all have been through many different levels of comfort and nervousness in our early days.
Congrats on going for your permit, and stay safe.