Hello
I am planning to make an app which could be used between defined times and if the time is not between the defined time then the app would give a warning and close the app.
Originally thinking about making a parental control app for parents and their kids so the parents can tell when it is enough.

I am using C# to make everything possible and I am using a database (MYSQL) to get the details.
The following are my questions:
Which way I should save in the database for different parents the timezone?
How I make the app to use that timezone which the parents defined?
If the parent will change the timezone while the app working and the time when the app can work then how the app will recognize that the data changed in the database?

I am newbie and I would be thankful for example or open source and some explanation if it is possible.
Thank you in advance all of the answers.