Considering their size, worms eat at a cracking pace! Your worms should start working on scraps within a few days and finish them within 1 to 2 weeks. If you see large amounts of food, you may need to reduce the amount you are adding. 

It is best to start with a small amount of food scraps (about a handful every few days). The worm population will grow gradually and as the population grows, they will eat more! You can increase the amount of food scraps that you add as this happens.