Here's what you should be doing:
- Place your vehicle on a level area like a driveway.
- Ensure your vehicle is up to operating temperature and running.
- Pull the dipstick and with a clean cloth, wipe it off.
- Stick the dipstick back into the tube down to the bottom, then pull it out again immediately and check the level.
- Add an appropriate amount of fluid (half a pint is a good measure).
- Replace the dipstick back into the tube (if you don't you'll more than likely push fluid back up through the tube in the next step).
- Get back into the vehicle, with foot on the brake pedal and run the transmission slowly through the gears (Reverse, wait a second; neutral, wait a second; drive, wait a second), then back up through the gears the same way.
- Start over at step 3 until the desired level is reached.
Once the vehicle is up to operating temperature, you don't need to wait 20 minutes between each time you add fluid ... the temperature of the fluid in the transmission will bring it up to temp rather quickly. Also, and this is imperative, DO NOT OVERFILL YOUR TRANSMISSION. This will cause your transmission to spring another leak which will not fix itself.
EDIT NOTE: Check both sides of the dipstick for the proper level. Many times, due to a bend in the tube, the bottom side (whichever side that is at the time) of the dipstick will run down the sloped part of the tube and pick up residual fluid which resides on there. If you check the other side of the dipstick, you should see a distinct line of fluid (this should be the top side) which will give you a more accurate reading of fluid level.