You can transition to juices immediately, no need for OJ. A juice fast also needs to be broken like the Master-Cleanse with soup, etc. For my 25 day fast I broke for seven days - this is according to what fast experts in Europe recommend - I know that here in the US they say 1/2 the number of days you fasted.
P&B is best when you are back to solid foods and that is also the best time for a parasite cleanse which you could follow by another short Master-Cleanse to flush out the extra toxins.