What should be the time gap between the juices?

On average, maintain about a gap of about 2.5 hours between one juice and the next.

If you are sedentary throughout the day, which means you are not active / doing too much physical activity during the juice fast, 4-5 glasses of juices will be sufficient. 

If you are doing exercises / physical activity during the fast, you may drink upto 5-6 glasses of juice per day.

However, the best rule to follow is - drink the juice whenever you feel hungry :) If you do not feel hungry or have no desire to drink the juice even after 2.5 hours, feel free to skip it!