you can get away with eating them right away if you are using a slow cooker, or soup.
if you try to roast it, rotisserie it or fry it, stretch out your jaw first.
rigor mortis sets in VERY quickly in chickens. while humans its several hours, with birds it's almost immediately. when we buchered the rest of our last week, the birds that we put in the tub of water at the onset of our session were already seizing up by the time we finished (about 45 minutes to an hour).
i rotissieried one the same day i processed it a couple months ago (about 4-1/2 hours later), and it was like eating a shoe sole. literally, it would come off the breast in slabs, and was VERY hard to chew. i was chewing, but it seemed like i was just squeezing it, and when i opened my jaw it would just rebound to its original shape.
the finger was the only thing "eatable," and it was somewhat chewy, too.
all the chickens we've done over the years, and we'd never tried eating one the same day. i had intended before we started, to eat one, but by the time we finished processing them, i had had enough of chickens. i did anyway, because my wife wanted one (she was not there)
i agree with the above poster who said your bird has already been "resting" for several days before you got it at the grocery store. still though, in my experience (in no way saying anyone else is wrong, this is just MY experience) overnight to 24 hours is all that is needed. the bird has rested by that point, and you're just dehydrating it past that point. this is just MY experience, and experience from a butcher who has been doing it for 40 years. that's not saying anyone else is wrong, just saying i don't believe any longer is necessary.
i will say, though, anyone telling your a chickens "cures" like beef, is not correct. it may taste differently, but that is not because bacteria is working in a "good" way