Real time calendar with daily events stored in it

Hello everyone, in my current project that I'm working on, there are events that a user can add that they have completed, which goes into a list.

What I want to do now though is, make it so each event is categorized into only the current day displayed, real time. Once it is the next day, it will be a clean slate and you can begin adding in events for that day. I also would want the player to be able to look back on previous days and those day's events.

I know how to display a realtime clock in game, but I'm wondering how complicated it would be to do what I stated above?