first day of month&las day of month

Try this VBA routine...change as required

Sub LastandFirstDayOfCurrentMonth()
Dim dYr As Double, iMth As Integer
Dim sMth As String
Dim LastDay, LastDayDate, FirstDay, FirstDayDate
Dim sMsg As String

dYr = Year(Now)
iMth = Month(Now) + 1
sMth = Format(Now, "mmmm")
'Get last day info
LastDayDate = Format(DateSerial(dYr, iMth, 0), " dd/mm/yy")
LastDay = Format(DateSerial(dYr, iMth, 0), "dddd")
MsgBox "The last day of the current month of " & sMth & " is " & LastDay & LastDayDate

'get 1st day info
FirstDayDate = Format(DateSerial(dYr, iMth - 1, 1), " dd/mm/yy")
FirstDay = Format(DateSerial(dYr, iMth - 1, 1), "dddd")
MsgBox "The 1st day of the current month of " & sMth & " is " & FirstDay & FirstDayDate

End Sub

HTH

Ivan