DebbieB - thank you for explaining the timetables. I just tried them and now I understand. If you put in a date that is not 330 days out, it will bounce back that the dates are invalid.
It appears that I have to wait until my return flights, and not my departure flights, are 330 days out otherwise it bounces back with an error.
Thanks again for all your help. It looks like August 5 is the day I'll be contacting USAir. I'm so psyched with the great time schedule they have, I really hope this works out for me.
Now the only other hurdle is my 3rd free flight is through my credit card, and they won't let me book until 10 months prior, so I'm keeping my fingers crossed there are still available seats around August 21.