How to work with clock in arduino?

Question

Arduino

I want to make something like an alarm clock. When the set time is reached, perform a certain action. I connected a real-time clock ds1307 so that the clock does not fly off when rebooting. But here's how to calculate when rebooting at the start, what needs to be done, for example, after 1 hour 2 minutes and 13 seconds?
There will be several such alarm clocks. Those. e.g.
1 at 04:00
2 at 12:44
3 at 14:05
etc. quantity may vary.

Answer 1

It's not entirely clear what the problem is.
Clock chips usually have non-volatile RAM. Maybe from its presence it is necessary to push off?