Well, beyond that, here's what helped me in the beginning. You can learn this by yourself.
Develop a two handed throw to your self that is flat (parallel to the ground) and floats down gently. Start by placing each hand on the outside of the rim, one hand close to you, the other on the far side of the rim. Throw your hands and arms out to the sides, popping the disc gently up in air, about a foot or two in height above you head.
Practice this skill alone, without attempting the delay, until you get the disc to float very horizontal and with as much spin as possible. Like a spinning top, the more RPMs the disc starts with, the more stable and easy to control it will be. The flatter it is, the easier it will be to balance and delay.
Once your self throws are stable, you are ready to proceed. Side note: If your right hand is the one close to you, your spin will be counter-clockwise. If you left hand is the one close to you, the spin will be clockwise. One spin may be easier for you to throw and one spin will be easier to delay at first. Make observations about your tendencies and what works best for you.
Make sure the contact with the disc is with your fingernail, however small it is (artificial nails are not necessary in the beginning). Hold you finger, slightly bent, so that the nail itself is close to parallel to the surface of the disc. This way the spinning disc will slide on your nail.
Apply a silicon spray lubricant to the disc to further reduce friction between the disc and your nail. As soon as the disc contacts flesh, there's major friction involved, usually leading to loss of spin and control.
Next, connect the above two skills. After you release the disc into the air, reach up to the disc with your delaying hand and try to make contact with the disc as close to the time when it is transitioning from popping up to floating down. The disc is traveling slow at this time. Spot the center of the disc as it's above eye level. Keep your finger kind of springy to absorb the contact of the disc with your finger at this time and follow the disc's descent with your arm to slow its further descent.
If you can keep the disc above eye level at this time, you can continue to spot your finger on the bottom of the disc and track your centering attempt. Eventually your eye-hand coordination will develop, allowing you to stabilize the disc below eye level, without seeing your finger on the bottom of the disc. A clear or translucent disc can also be helpful at this stage.
Finally, make small circular motions with your arm and finger, in the same direction that the disc is spinning. This motion will help correct any non-horizontalness of the disc and helps you track to the center of the disc to maintain the delay. Over time, these motions become so refined that you will not even realize that you are making them.
Eventually you will replace step 1, with that of a throw from a partner. Make sure your throwing partner is throwing you the same spin that you practice with or everything will seem awry. If your partner can make a hovering throw, again try to make contact with the disc at a point in its flight where it is transitioning from flight to fall. Let your finger and arm give with the disc as you receive it, acting as a shock absorber to slow its momentum to a standstill.
The whole process is learning this eye-hand coordination. Players have reported different lengths of time to learn the skill from less than a week to maybe six weeks. A youthful age and athletic tendencies will tend towards the shorter time. Practice every day for at least fifteen minutes and you will see results of increasing delay times.
Once you're comfortable in maintaining a delay, ask questions about the next level you want to attain.