You will most likely not experience any benefits, if you just add several glasses of juice to your present diet, or if you fast on juices one day, eat usual food other day and so on.
To get benefits of elimination, you have to eliminate everything but juices for at least 48 - 96 hours, or for a week.
Drink some magnesium sulfate or citrate or magnesium chloride every morning to flush your intestines clean.
Any food kept inside intestines will delay healing process.
healing process may be delayed even for several weeks, if person is 100% constipated while on juices.