Giving it a week at serving pressure ensures that the CO2 is absorbed throughout the beer evenly, but I like zeekage's idea too. Try it after a day or two and keep trying and see how it changes. I've done this on many batches mostly because I am eager to drink my new batch. After a day or so at serving pressure it will have a lot of head, but not a lot of CO2 in the beer itself, and as time goes in it will become more saturated into the beer. I have enough of a pipeline now where I just hook it up, forget about it for a week, and by the time I'm ready to drink the new batch, its ready.