It depends partly what you're juicing I think. Green veges only might cause a bit of major die off if you were used to some sugars/simple carbs before your fast.
The other thing to remember is that juice fasting will cause all kinds of toxins to be released and broken down (not just Candida), and withdrawal symptoms, and it's common to feel pretty bad off and on over the first week of a fast. Using psyllium and Bentonite plus a lax tea or salt water flushes during a juice fast can mean the toxins (whatever they are!) are expelled quickly and without causing you as much grief!