Countdown timer for Storyline 360 - not in results slide

I recently created an EKG rhythm interpretation exercise for our nursing staff and I could see adding a timer in the future to up the challenge. But I like doing stuff like this just to refresh on some of the features i don't use very often. It took me longer to remember how to create the ability for the user to enter the desired times and then get them to work than it did for most of the rest of it.