Waiting and having amazing sex with the right person beats having sex because you're "supposed to" any day. Please don't stress yourself out. In my experience men last longer when they are having sex on a regular basis. So don't put everything on your first time. You'll never forget your first time, but guaranteed it won't be your best time. The more you practice the better it gets. I know it is a big deal to you and your feelings are valid. Just try not to let it get to you too much.