Now that you've set up your Punch Clock, follow these steps to pin the app to the screen and always keep it active.
To Pin App :
Open Settings > Accessibility > Guided Access
Turn ON Guided Access
Select "Never" in Display Auto-Lock
Open Punch Clock App
Quickly Press Home Button x 3
Tap "Start" - you'll be asked to create a Passcode
To Unpin App:
Quickly Press Home Button x 3
Enter Passcode
Tap "End"