public partial class Form1 : Form
{
private System.Windows.Forms.Timer[] ts = new System.Windows.Forms.Timer[6];


public Form1()
{
  InitializeComponent();
  
}

void t_Tick(object sender, EventArgs e)
{
  ((System.Windows.Forms.Timer)sender).Enabled = false;
  SendKeys.SendWait("{Enter}");
}

private void button1_Click(object sender, EventArgs e)
{
  Action act = new Action(() => 
  {
 for (int i = 0; i < 6; i++)
 {
   ts[i] = new System.Windows.Forms.Timer();
   ts[i].Tick += t_Tick;
   ts[i].Interval = 2000;
   ts[i].Enabled = true;
   MessageBox.Show("MsgBox" + (i + 1));
   Thread.Sleep(2000);
 }
  });
  act.BeginInvoke(null, null);
}

}

Public Partial Class Form1
  Inherits Form
  Private ts As System.Windows.Forms.Timer() = New System.Windows.Forms.Timer(5) {}


  Public Sub New()

    InitializeComponent()
  End Sub

  Private Sub t_Tick(sender As Object, e As EventArgs)
    DirectCast(sender, System.Windows.Forms.Timer).Enabled = False
    SendKeys.SendWait("{Enter}")
  End Sub

  Private Sub button1_Click(sender As Object, e As EventArgs)
    Dim act As New Action(Sub() 
    For i As Integer = 0 To 5
      ts(i) = New System.Windows.Forms.Timer()
      AddHandler ts(i).Tick, AddressOf t_Tick
      ts(i).Interval = 2000
      ts(i).Enabled = True
      MessageBox.Show("MsgBox" & (i + 1))
      Thread.Sleep(2000)
    Next
End sub)
    act.BeginInvoke(Nothing, Nothing)
  End Sub

End Class