If you want to hear my opion whether to do a flush or not and working the next day from 4 p.m. on:
I would definately say NO!!.
The reason why: Beeing relaxed and confident during the entire Liver-Flush time is of utmost importance and the key to a real sucessfull flush. At least this is my experience. Facing the fear of maybe not being ok the next day will make you sort of tense and prevent a full relaxation mental wise and bodywise.