Mod works like this:
1. check what day is it
2. is it the same day as day stored in a value called "previousDay"
3. if yes, do nothing
4. if no, show message and set previousDay to currentDay value


This is the trick - it doesnt store ticks. It just checks the day and show message when the day is different to previous, stored value. I dont see a room here to implement functionality you want.


Also, when dealing with precise timing, think of a lag, disconnects etc. The precision you want is simply unachieveable withouth server-side tool. For example, 2b2t time is so chaotic and the time measurements on this server are their own history.

It is because minecraft start on day 0, not day 1. So when you login to the just created world, the time is Day 0 and this addon then displays Day 1.