That would be best, but few can afford the luxury of having fresh squeezed juice every hour during the day. If you juice your orange for the day, you would still be better off than some (or maybe just me; I pick mine from the fridge of a health food store and just make sure it is fresh, no preservative, and non-pasturized).
I also use a variety of fruit juices, alternating every couple of days, and I still get results. But I do take herbs for anything that may be lacking with this method. My favorite herbs to take during a fast is the longevity spices and the herb spray III; no lbb needed.
Since this is your first time, you may want to just use oj and see what effects it has on you.