As the saying goes, long time time reader, first time poster. This seemed to be the best place for this thread?

I need to be in Charleston for a wedding on August 16th. My tentative plan is to fly MSP-CHS on Sat. the 15th and CHS-MSP Wed. the 19th. Fares have been pretty steady around $400.00 for Y and $700.00 for F for the last week.

The issue is because of work I won't know the exact times or dates I will be able to depart or return, and won't know my work schedule until a few weeks to a month out.

I have little knowledge on refundable or flexible fares, or the different fare classes and rules. Are there any decent options to book in advance for someone in this position? Or should I just buy a last minute ticket and spend the extra money? Does buying an F ticket help at all? DL, UA, and AA all have very similar prices currently, and I'm not loyal to any airline.

Thanks!