Count down timer in vb.net - vb.net

Question

In the following code I have a timer that counts down from 5 mins. I am trying to have a visual count down timer in a lbl in mm:ss but the example I used doesn't work. It counts down but doesn't update the lbl until it hits 00:00.
The asker of the following question (were I got the code) said it works perfectly but for me it doesn't at all.
The Example I used
My code:
Private Sub Form1_Load(sender As System.Object, e As System.EventArgs) Handles MyBase.Load
picLogo.SizeMode = PictureBoxSizeMode.StretchImage
'Timer until update
tmrUpdate.Interval = 300000 '5 minutes
TargetDT = DateTime.Now.Add(CountDownFrom)
tmrUpdate.Enabled = True
End Sub
Private Sub tmrUpdate_Tick(sender As Object, e As EventArgs) Handles tmrUpdate.Tick
Dim ts As TimeSpan = TargetDT.Subtract(DateTime.Now)
If ts.TotalMilliseconds > 0 Then
lblTimer.Text = ts.ToString("mm\:ss")
Else
lblTimer.Text = "00:00"
tmrUpdate.Stop()
End If
End Sub

Answer 1

Answer:
Using a Async Sub I had the count down timer running while other stuff was going on in the back ground. This way the app could still be used during the Sub Wait() and this code also displayed the count down timer.
Used one timer on a 1 sec interval.
Private Async Sub DoStuff()
'Doing stuff
timeUpDate = 599
tmrUpdate.Start()
Application.DoEvents()
Await Task.Run(Sub()
Wait()
End Sub)
Loop
End Sub
Private Sub Timer1_Tick(sender As Object, e As EventArgs) Handles tmrUpdate.Tick
Dim hms = TimeSpan.FromSeconds(timeUpDate)
Dim m = hms.Minutes.ToString
Dim s = hms.Seconds.ToString
If timeUpDate > 0 Then
timeUpDate -= 1
lblTimer.Text = (m & ":" & s)
Else
tmrUpdate.Stop()
lblTimer.Text = "text"
End If
End Sub
Private Sub Wait()
Threading.Thread.Sleep(600000)
End Sub