Cooking times will depend on the weight of your chicken: On high, you'll cook it for 3-4 hours. On low, you'll cook it 6-7 hours.
I put my chicken in breast side up even though the author of the original recipe cooked hers the other way. Mostly out of habit and/or lack of reading comprehension. :)
Add NO liquid to the slow cooker whatsoever and put on the lid. Try your hardest not to open the lid while it cooks - all it's going to do is add time!
Once the legs begin to separate from the body of the bird, it's close to being done. It's a good idea to double check to make sure the chicken has reached 165 F (check the thigh!) and is cooked all the way through. If you have a crockpot like mine, you can even insert a probe and stop the cooking right when it hits that temp.