Option Explicit
Private Sub Worksheet_Change(ByVal Target As Range)
If Target.Address <> "$A$1" Then Exit Sub
Application.EnableEvents = False
[B4].FormulaR1C1 = "=DATE(RIGHT(R1C1,4),1,1)"
[C4:JC4].FormulaR1C1 = "=RC[-1]+(WEEKDAY(RC[-1],2)=5)*2+1"
With [B3:JC3]
.FormulaR1C1 = "=IF(MONTH(R4C)<>MONTH(R4C[-1]),TEXT(R4C,""mmmm""),NA())"
[B3].FormulaR1C1 = "=TEXT(R4C,""mmmm"")"
.SpecialCells(xlCellTypeFormulas, 16).ClearContents
.HorizontalAlignment = xlCenterAcrossSelection
With .Borders(xlInsideVertical): .LineStyle = xlContinuous: .Weight = xlMedium: End With
End With
[B5:JC5].FormulaR1C1 = "=MID(""LuMaMeJeVe"",2*WEEKDAY(R[-1]C,2)-1,2)"
Application.EnableEvents = True
End Sub