Sub savefichier()
Dim chemin$, dat As Date, f, a&, oldfich$
chemin = ThisWorkbook.Path & "\"
BaseName = "monfichier"
dat = Now()
f = Dir(chemin & "monfichier*.xls*")
Do While f <> ""
a = a + 1
fdt = CDate(FileDateTime(chemin & f))
If f <> ThisWorkbook.Name Then If fdt < dat Then dat = CDate(fdt): oldfich = chemin & f
f = Dir
Loop
If a >= 3 Then Kill oldfich
ThisWorkbook.SaveCopyAs chemin & BaseName & "_" & Format(Now, "dd-mm-yyyy hh""H""mm""m""ss") & ".xlsm"
ActiveWorkbook.Save
End Sub