We have been worm farming now for a few years, and have millions of earthworms (Red Wigglers - Eisenia foetida)
Remember that earthworms consume about half their own weight in food every day under ideal conditions. So if you are planning to give them 500 grams of kitchen foodscraps a day (household of 4), you will need at least a kilogram of worms. What is the use of having a bin full of food and only a few worms to consume it all. And if you are like me, instant gratification rules. Show me the results.
Earthworms are available in batches of ± 1000 worms. We follow the internationally accepted standard of extracting the worms out of the vermicompost, and then weighing them, with 1000 worms weighing approximately 250 grams.