Private Sub Worksheet_Change(ByVal Target As Range)
On Error GoTo A
r_ = Range("a" & Cells.Rows.Count).End(xlUp).Row
If Target.Row = r_ And Range("a" & r_) <> "" Then
    n_ = Format(Range("a" & r_), "MMMM YYYY")
    s_ = ThisWorkbook.Sheets.Count
    Sheets("Øàáëîí").Copy After:=Sheets(s_)
    Sheets(s_ + n).Name = n_
End If
Exit Sub
A: MsgBox "Ïðîâåðü, íåò ëè ëèñòà ñ òàêèì èìåíåì."
End Sub

Private Sub Worksheet_SelectionChange(ByVal Target As Range)
On Error GoTo A
r_ = Range("a" & Cells.Rows.Count).End(xlUp).Row
If Target.Row <= r_ And Range("a" & r_) <> "" Then
n_ = Format(Target, "MMMM YYYY")
    Sheets(n_).Activate
End If
A:
End Sub