SSIS 2008 WMI Event Watcher Automatic Stop Execution

Hi,

I have a requirement to automate a process where my SSIS package will be running from SQL Job.The requirement is to start the package automatically when the file arrives in a particular folder and the package should automatically stop after the load means the WMI Event watcher should not be checking the existence of the file again.Can anyone suggest me how to accomplish this.

Thanks in advance