How do I reference the sheet named 20 (for the day of the month), then tomorrow the With Sheets("20") will be With Sheets("21")?

Sub Macro1()

With Sheets("20")
'.do stuff
End With


End Sub

On the worksheet in a cell =Today() and then custom formatted "d" returns 20.
Tomorrow I presume it will return 21.

How do I make that happen in the code?

Howard