I take one pill 45 minutes to an hour before take-off (so it's in my system). If it's a long flight, or if I feel particularly uncomfortable during the flight, I take a 1/2 of an additional pill. (I don't know the strength of my dosage, but the bottles says "take 1 or 2 pills," so the 1 and 1/2 is fine for me.
I still don't like it (flying), but the Xanax manages to take the edge off. Just take deep breathes. That's key. It keeps you from hyperventilating, helps with your circulation, and discourages nausea.
You're certainly not alone!!!