Run Function at a specific date time

I’m working on an app that will be running on a tablet all time. I need to schedule the function at a specific time. Meaning each time at 8:30 AM, the function will execute once. It would be much better if I can pass also a Date Time at the same time. Meaning, I need to run a function on 2018-09-11 12:30.000, Once!!

Include background process plugin and set timer within it to check if the time is the one you are expecting. set timer to 3 hour till it is less the 8 am then set it to 1 min and gain reset it back to 3 hour once the time is over