How to save as txt file name depend on current date and time

Sub txt()
 Dim myFile As String, rng As Range, cellValue As Variant, i As Integer, j As Integer
  
  
  myFile = "C:\Users\abc\log.txt"
  
    Sheets("log").Select
    Range("A1:M1").Select
    Range(Selection, Selection.End(xlDown)).Select
  
  Set rng = Selection
  Open myFile For Output As #1
     For i = 1 To rng.Rows.Count
     For j = 1 To rng.Columns.Count
  cellValue = rng.Cells(i, j).Value
  
  If j = rng.Columns.Count Then
     Write #1, cellValue
Else
     Write #1, cellValue,
End If
     Next j
Next i
  Close #1
  
  
  
  
End Sub