How to execute a method based on specific date in c#

Basically, you need to have some Windows Service which could start an application on certain conditions.

Such service already exists, It is designed to support really complex schedules. It is already bundled with Windows and enabled; you can use it on different levels. It is called Window Task Scheduler, see http://en.wikipedia.org/wiki/Windows_Task_Scheduler[^].

First, you can schedule events using command-line utilities AT.EXE or CSHTASKS.EXE (which is replacing AT.EXE), see:
http://en.wikipedia.org/wiki/At_%28Windows%29[^],
http://en.wikipedia.org/wiki/Schtasks[^],
http://technet.microsoft.com/en-us/library/bb490866.aspx[^],
http://msdn.microsoft.com/en-us/library/windows/desktop/bb736357%28v=vs.85%29.aspx[^].

And you also can use Window Task Scheduler API, please see:
http://msdn.microsoft.com/en-us/library/windows/desktop/aa383614%28v=vs.85%29.aspx[^],
http://msdn.microsoft.com/en-us/library/windows/desktop/aa383608%28v=vs.85%29.aspx[^].

To see how can you use it with .NET, see this CodeProject article: A New Task Scheduler Class Library for .NET[^].

[EDIT]

In response to follow-up discussion: please see:
http://en.wikipedia.org/wiki/Push_technology[^].

—SA