There are some advantages to chilling it for a few days before drinking - the biggest one being that more CO2 will get absorbed into the beer, and more evenly. You'll usually get a better head on the beer. Also chill haze will usually be reduced after a week or more in the fridge, and the beer will be clearer. More cold time also compacts the sediment on the bottom of the bottle, making it easier to leave behind when pouring.
I don't do it all the time, but I notice the difference when I do. When I'm tasting the first one from a batch, I usually just give it an overnight chill but once I've decided they're ready, I'll pop 12 or more of them in there, and rotate out and drink the ones that have been in the longest.