Originally Posted by
Often1
You can do all the legwork first and then simply call it in. No need to make quick decisions. But, in any event, remember that you have 24 (actually more) hours to cancel penalty-free, so you don't have to worry about not being able to see what you've done.
I don't think that's actually true in this case. Stored flight credit that hasn't been converted to an ETC is left on an existing PNR, meaning that when you're using it on a new set of flights, you're actually completing a change (hence, the change fee, which must be paid in new money), and not a purchase. There is no 24-hour grace period for changes.