@xahteiwi probably fairly quickly. It would likely more depend on my relationship with the person.
If they are a close friend I'm likely to spend far more effort nudging them and helping them. Likely going through several 'complaint' cycles.
If they were an acquaintance, then likely much shorter. I'm probably only wish to listen to them a couple of times, before being a bit more direct in telling them to lump it or like it, and I've had enough of hearing them moan.