Ryan Young gives us a great practice technique for the rim delay. Basically, try to keep the disc in the same location in front of you while keeping the disc sliding on the rim, on your finger nail. To do this, rotate your hand in a circle the same direction as the disc is spinning. Also, move your wrist and finger so the disc does not touch your skin, only your nail. Lastly, move your elbow and other body parts out of the way so the disc will continue to rotate freely.
This technique is a stepping stone to mastering control over the rim delay, being able to give yourself any nose you desire, and to learning to go from the rim to the center delay.