I made a 10 gallon batch of Centennial Blonde a couple weeks ago, and on a whim, racked one of the carboys (5 gallons) onto 2 lbs raspberries. It wasn't until later that I realized that I probably should have saved the fruit until the secondary, but too late now. I did look around, and see that it isn't unheard of to add the fruit to the primary, but there doesn't seem to be much advice as to whether having fruit in the primary effects how long it should remain in the primary before being racked to the secondary.
That said, does anyone have any advice as to how to tell when to transfer? Should I just rely on seeing whether the SG drops over a period of a few days (as I typically do) or is there more to consider with fruit? I want to be sure that the raspberries have been fully utilized (both to ensure that the yeast has consumed all the additional sugar, and to get as much flavor as possible.)