Count Characters left of a hyphen

[BukHix]

I have a series of job numbers like this

K3444-
K5633-
3434-
3434- A
3434- B
M3456-

I need to count the characters left of the dash and then add a leading space to those that only have 4 characters. It should look something like this:

K3444-
K5633-
  3434-
  3434- A
  3434- B
M3456-

So far (with the help of another thread on this forum) I have been able to figure out how to count all the characters in the textbox and add the spacer with this:

Dim strCharCount As String = txtJobNumber.Text
        strCharCount = RTrim(strCharCount)
        Dim iLength As Integer = strCharCount.Length
        If iLength >= 5 Then
            strCharCount = strCharCount
        ElseIf iLength = 4 Then
            strCharCount = " " & strCharCount
        ElseIf iLength <= 3 Then
            MsgBox("You must use a valid Job Number.", _
                MsgBoxStyle.OKOnly, "Length Error!")
            txtJobName.Clear()
            txtJobNumber.Focus()
            Exit Sub
        End If

How do I modify this to count only the characters left of the - (dash)?