How to run method on schedule?

Good afternoon. For example, a typical application in WinForms, there is a method HelloWorld
public void HelloWorld()
 MessageBox.Show("Hello world!");

How to make this method be called on a schedule? One of the conditions - schedule to be set manually, without harkada.
Googled and Ncron, but honestly could not understand. So please some example code for a specific task.

Variant with Timer, endless stream, etc. are not suitable.
September 18th 19 at 23:50
2 answers
September 18th 19 at 23:52
And can add to the application class library exporting a function that will call the desired method (though I don't understand how she is going to call a method of the form, because you need to run the whole form, i.e. the application) and call it from windows scheduler via rundll32?
September 18th 19 at 23:54 - we'll see. There is great detail through the work
Sources at end of article.
Thanks, seen. But did not understand how to make what is written in the question. And therefore asked the code in my example. - kyleigh commented on September 18th 19 at 23:57

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