If you followed the instructions, the propeller should be installed properly. There is a step in which you are supposed to remove the rubber spinner and flip the prop over. Did you do that step?

The launching method described in the instructions works well, too. You're supposed to launch with the power OFF, so the spinning prop doesn't hit your fingers. That said, I've launched power-on more times than power-off, and never came near my fingers with the spinning prop. The follow-through in your throw should bring your hand well clear long before the prop gets close.

Getting a good launch does take some practice. I've flubbed more than a few. If you throw too hard, the plane flips up out of control, stalls, and crashes. Give it a good stiff toss straight ahead, then add power.

Being left-handed, I have a bit of an advantage. I can control the elevons and launch at the same time.