You can use a FileSystemWatcher to check if the specific folder is created in a specific location. When its created you can start the Windows Service.
Creating FileSystemWatcher
//Define this in the clas level
FileSystemWatcher watcher = new FileSystemWatcher();
Initializing
private void InitializeWatcher()
{
watcher.Created += new FileSystemEventHandler(NotifyChange);
watcher.Path = @"E:\here\folder";
watcher.EnableRaisingEvents = true;
}
Starting Windows Service when folder is created
private void NotifyChange(object sender, FileSystemEventArgs e)
{
if (e.Name.Equals("FolerName",StringComparison.OrdinalIgnoreCase))
{
new ServiceController("WindowsServiceName").Start();
}
}