I have used the following code to format the cells in my spreadsheet. I copied this from a website so I don't actually know what it means! It's working fine but I would like to be able to format by the first three letters in each cell, not just the first letter. I am a complete novice and any help would be hugely appreciated.

Thanks in advance 

Option Explicit
Private Sub Worksheet_Change(ByVal Target As Range)

Dim vLetter As String
Dim vColor As Long
Dim cRange As Range
Dim cell As Range
  
Set cRange = Intersect(Range("A17:A65000"), Range(Target(1).Address))
If cRange Is Nothing Then Exit Sub
   
For Each cell In Target
      vLetter = UCase(Left(cell.Value & " ", 1))
   
     vColor = 0
     Select Case vLetter
        Case "T"
            vColor = 34
        Case "P"
            vColor = 37
        Case "G"
            vColor = 39
        Case "M"
            vColor = 38
        Case "C"
            vColor = 40
        Case "A"
            vColor = 36
      
     End Select
     Application.EnableEvents = False
     cell.Interior.ColorIndex = vColor
     Application.EnableEvents = True
   Next cell

End Sub