Problem with refreshing textbox

[kokon]

In the code below DayTicker is started by

timer1.Tick += new EventHandler(DayTicker);

void DayTicker(object sender, EventArgs e)
{
  timer1.Stop()
  richTextBox1.Text += "\nTESTTTTTTT\n";
  myProcess(0, 0, 0);
  CheckTheOutput();

public void myProcess(int first, int second, int third)
        {
            Process proc = new Process();
            proc.StartInfo.WindowStyle = ProcessWindowStyle.Hidden;
            proc.StartInfo.CreateNoWindow = true;
            proc.StartInfo.UseShellExecute = false;
            proc.StartInfo.RedirectStandardOutput = true;
            proc.StartInfo.FileName = "test.exe";

            proc.Start();

            StreamReader myStreamReader = proc.StandardOutput;
            OutputLog = myStreamReader.ReadToEnd();

            richTextBox1.Text += OutputLog;
           
            
     
        
        }

Process test.exe takes about 2 min to complete. And after that time textBox is updated with the text: "TEST" and test.exe output.
But text: "TEST" should appear before the execution of the process, not after proccess is ended.
Please help.