I booked SEA-NRT-ICN for 9/16 with a return of 9/23. I meant to book the return for 9/21 (I had the option of doing week of 16th and week of 23rd so 23rd was stuck in my head when I emailed our corporate travel).

I tried to rebook now but because they have to requalify the whole round trip the price of the ticket more than doubles (only B fares available outbound now). Is it better to wait until I have taken the outbound flight and then rebook the return? Also, do I have any hope of trying to at least stand by on Saturday (if not Friday)?