That's a funny example to use, since you can move up a date, but nobody talks about moving down a date. Same problem in the opposite direction.
"We're moving up the launch" is common, but never heard anyone say "we're moving down the launch", even though delays are common.
The issue with "prepone" is that "pone" isn't really used as a world. A quick googling shows that it is a word, but in regular speech it's not used as a standalone.
"We're moving up the launch" is common, but never heard anyone say "we're moving down the launch", even though delays are common.
The issue with "prepone" is that "pone" isn't really used as a world. A quick googling shows that it is a word, but in regular speech it's not used as a standalone.