Initial capital customized

[snb]

strconv() is your friend:

Sub M_snb()
   sn = [B3:B12]
   
   For j = 1 To UBound(sn)
     sn(j, 1) = Replace(Replace(StrConv(Replace(Replace(sn(j, 1), ".", ". "), "/", "/ "), 3), ". ", "."), "/ ", "/")
     If sn(j, 1) Like "*[0-9]*" Then sn(j, 1) = UCase(sn(j, 1))
     
     For Each it In Split("di da con per mm in a e la le")
       If InStr(1, sn(j, 1) & " ", " " & it & " ", 1) Then sn(j, 1) = Replace(Replace(sn(j, 1), UCase(it), it), StrConv(it, 3), it)
     Next
   Next
   
   [K3:K12] = sn
End Sub