I am creating  a method which is measures the copy time for files and folder.

 public static TimeSpan CopyFileExplorer(string filePath, string fileDestination) 
    { 

        string command = @"/select, " + filePath; 
        System.Diagnostics.Process.Start("explorer.exe", command); 
        SendKeys.Send("^(C)"); 
        command = @"/select, " + fileDestination; 
        System.Diagnostics.Process.Start("explorer.exe",command); 
        DateTime startCopy = DateTime.Now; 
        SendKeys.Send("^(V)"); 

        //need to be catched when explorer finishes the copy 
        DateTime endCopy = DateTime.Now; 

        return endCopy - startCopy; 
    }

I have tried to find when the "copy window" of explorer disappears, but I didn't be successful...