Not worried too much on here or eBay when you have normal classifieds.
However if an auction, you need make sure it ends at a sensible time and not something like 3am!
I have found a few times that when I placed an ad Sunday mid morning I had at least offers on it the same day. Even sales same day a few times.
I think it is more dependent on you selling an in demand product at a fair price than when you list it imho.
