Originally Posted by
Elizabeth208
Well, shoot, thanks for the information. No wonder I couldn't find any details/rules about this on DL.com
I assumed, that a person could just call up 24 hours ahead of time and request the change at lickety split, it would get done.
The reason it's challenging in economy is that there needs to be the same fare on your new flight. So buying far in advance on an a 'deep discount economy' fare is going to be hard to find day-of travel. However, when flying in first class, any (non-Delta-One) space is allowed for SDC. There's a helpful wiki page about it on Flyertalk:
Same-day confirmed and same-day standby options