How to change day & time in 12hr that moves when pressing a button

I'm trying to create a ingame time that is NOT in real time, meaning that time will only change when pressing buttons.

The UI should look something like this: Monday 8:00AM

Scenario Example: Lets say there are two buttons, ButtonA and ButtonB. ButtonA will add 40minutes to the current time and ButtonB will add 20 minutes to the time. Just like the real world concept, the day name should change too once it reaches the next day. So basically a cycle from monday to sunday with the time.

Thanks!