Add a milestone
You give it a name and a time, then tap Save.

Add the next thing with a name and a time. The countdown shows up on your Lock Screen.
Try it free for 7 days, then unlock Pro once for $4.99.
You give it a name and a time, then tap Save.
The next thing stays on your Lock Screen with a live countdown. Wake your phone and you see what it is and how long you have.
On iPhones with Dynamic Island, the countdown can show there too.
Open the app to see your next few hours, each thing with its name and time, and a line at Now.
Free for 7 days. Then $4.99, once.