My $C$4 is a List (Jan, Feb, ...Dec)
I have a table (Range) mydates
as follows:

Name Month# Column#Start
Jan 1 3
Feb 2 5
Mar 3 7
Apr 4 9
May 5 11
Jun 6 13
Jly 7 15
Aug 8 17
Sep 9 19
Oct 10 21
Nov 11 23
Dec 12 25


Private Sub Worksheet_Change(ByVal Target As Range)
'On Error Resume Next
Dim vcol1 As Integer
Dim vcol2 As Integer
Set mydates = Sheets("Sheet1").Range("A2:C13")
If Target.Address = "$C$4" Then
vcol1 = Application.VLookup(Target.Value, mydates, 3, False)
vcol2 = vcol1 + 1
For Each c In Range("E7:Z7")
If Val(c.Column) < vcol1 Or c.Column < vcol2 Then
c.EntireColumn.Hidden = True
End If
Next
End If

But the above is hiding EVERYTHING -- Trying to work out for 3 hrs... grrrrr
withlut success///