Anything beyond a week or at most two, after the scheduled bottling date and you're going to need to think about topping. For me a month would be too long.
If you're making country wines (like I do) then I'd strongly recommend a sulfite testing kit to hit and maintain a decent sulfite level at bottling. Test, add, test and then top up for any extended ageing. Oxidation is the number one flaw I see in judging country wines