Start a story that begins with the ending, then immediately jumps back in time.
e.g. “It all started 12 hours ago.”
Think of this as the way someone might shoot a heist movie: a character is being led out in handcuffs and a voiceover says, “It all started 12 weeks ago.”
(In a short story you probably need to keep the scale in hours as this means you don’t have too many scenes.)
Don’t worry too much about getting this perfect. Feel free to be cheesy. Just have fun. Leave a comment to let us know how you got on!