I know that enemas or colonics would be best, but I live in a rural area and it is hard to come by.
I generally take one shake a day as a maintenance. I take it at night as I take my meds and vitamins in the am. IF you do add a am shake, I would wait 1-2 hours afterward so your meds would not be absorbed.
If I am flushing, I try to do twice a day shakes, the week before and the week after. I have never had headaches or the such from a flush. I attribute it to the P&B shakes absorbing the nasties.