how to run a macro automatically in a particular sheet

[tabspace]

I have the following macro:

Sub Do_it()

If Now > 43466 Then Range("C:D,F:F").EntireColumn.Hidden = False ' 43466 is Jan 1 2019
If Now > 43497 Then Range("K:K,P:P").EntireColumn.Hidden = True ' 43497 is Feb 1 2019
If Now > 43525 And Now < 43534 Then Range("W:Z").EntireColumn.Hidden = False  ' march 1~10 2019

End Sub

I want it to run automatically when the file is opened, but only in 2 particular sheets, lets say "SHEETA" and "SHEETB"

Can anybody help me with this?

Thanks!

 

[mumps]

(Untested) Place this macro in the code module for ThisWorkbook. Do the following: Hold down the ALT key and press the F11 key. This will open the Visual Basic Editor. In the left hand pane, double click on "ThisWorkbook". Copy/paste the macro into the empty window that opens up. Close the window to return to your sheet. Save the workbook as a macro-enabled file. Close it and then re-open it.

Private Sub Workbook_Open()
    Application.ScreenUpdating = False
    Dim ws As Worksheet
    For Each ws In Sheets(Array("SHEETA", "SHEETB"))
        If Now > 43466 Then ws.Range("C:D,F:F").EntireColumn.Hidden = False ' 43466 is Jan 1 2019
        If Now > 43497 Then ws.Range("K:K,P:P").EntireColumn.Hidden = True ' 43497 is Feb 1 2019
        If Now > 43525 And Now < 43534 Then ws.Range("W:Z").EntireColumn.Hidden = False  ' march 1~10 2019
    Next ws
    Application.ScreenUpdating = True
End Sub