Yep, there are two approaches to starters. You can pitch the whole thing at high kraeusen, 18-24 hours into the life of the starter when the yeast is at peak activity, or you can let it ferment out completely, two or three days, chill in the refrigerator (at least overnight) to settle the yeast to the bottom, and decant most of the spent wort before pitching. Both ways work. At lot of it depends on the size of your starter and the delicacy of your target beer. A 1L starter in 5 gallons of ESB, Saison or fruit beer isn't going to make a damn bit of difference in its flavor while 3-4L of starter in a light lager or clean, crisp APA might.