Use Scale Keys to scale function curve keys horizontally.
Scale Keys: Changes the horizontal location and amount of time covered by selected keys.
The scale center for scale time is the current time set by the time slider. You can scale keys about any moment in time by dragging the time slider before you use Scale Keys.
Dragging right expands the keys away from the current time.
Dragging left shrinks the keys towards the current time.
Dragging left past the current time reverses the keys and expands the keys away from the current time.