Extending or pushing a deadline means giving more time to work on a project. But what if you want to say you are changing it so that the task is due sooner?
What are the words or expressions I could use?
Looking up dictionaries I found that prepone is actually a legitimate word.
to reschedule to an earlier day or time: Our Wednesday meeting has been preponed to Tuesday afternoon at 3:00.
It makes sense etymologically as well since postpone is a composite of post (after) and pone (place, position). Example sentences using the words prepone and preponement can be found here.
EDIT: As per the OED this word has etymological roots in Latin very much the same as the corresponding antonym. It derives from the classical Latin word praepōnere meaning to place in front.
The term extending the deadline is itself incorrect. You can only move the deadline, farther or nearer. "deadline: the latest time or date by which something should be completed."
The deadline runs across the timeline, representing a point in time: its length makes no difference :)
A similarly incorrect, though very common, phrase is extending the Last Date/ Due Date. The last date or due date is a point in time. One should be saying "extending the time for (completion/ action/ etc.).
You can say advancing the deadline.
Refer to Advance .
5: to bring forward in time; especially : to make earlier
Rescheduling any event so it's nearer to the present is often called bringing it forward, whereas the reverse is pushing it back.
The deadline was brought forward by one week
This idiom is defined in the Macmillan Dictionary, amongst other places:
bring forward: to change the date or time of an event so that it happens earlier