Instagram has added a new 'Countdown' sticker for Stories, which displays a timer for a chosen event.

The new option was first spotted by social media expert Matt Navarra, and full credit to the team from Later for their rundown (and screenshots) of the new functionality.
As you can see here, the Countdown sticker is now available within the Stories sticker tray - choose it, and you can then select the end date and time of the countdown, and the color of the sticker itself. You can then add the sticker to your story - but the real key element is this:

When a user taps on your countdown sticker, they'll be given the option to either set a reminder for when the countdown ends, or to share the countdown with their followers.
This could be a great addition for brands - now, you'll be able to set reminders for upcoming product launches or sales events, and maintain connection with your fans by helping them to maintain awareness of the date and time.
There's a wide range of ways in which this could be used - set up reminders for an upcoming Twitter chat, prompt users to review their settings, help your audience stay on track with upcoming events - and many more options to consider.
It's another tool to add into your Instagram Stories marketing approach for 2019.
The Countdown sticker is available now in Instagram Stories.