You need to take the tinctures a week before the flush, not right before. I take Chinese Bitters everyday, always will. I noticed that when I take both Coptis and Curcuma everynight for a week before a flush, that I get best results. I don't think that it's NECESSARY to take ANY herbs before a flush, I just think it probably helps keep your liver in better shape, and probably helps with recuperation and whatnot. I don't think that your flush will be effected too much one way or another.
You can take the olive oil and juice mixture anyway you want, I don't think it matters at all.
As for the magnesium citrate, I personally think it's best to take some kind of laxative to get the bowels moving, to get the stones out. It's so important to get those things out, and get your bowel cleansed so that toxins don't get recirculated. Magnesium citrate is seemingly very safe and effective. I also do an enema, and do p&b shakes as well.