The amount of airflow in the bin is another factor that is important. It is best to get a 'feel' for your own worm bin. Watch the food you put in, and when it has nearly gone, you can put more in. Over time, the feeding rate will become faster as your worm population increases. Part of the bedding material will be included in the worms diet as well.
Bedding is the name for the 'safe' material that the worms live in.
Something that is not likely to heat up and kill them. Materials that are carbon based are usually used. Aged' horse or cow manure can also be used. Then squeeze out the excess moisture till only a few drops come out, before placing in the bin. Place the worms on top, and they will bury down away from the light.