hmm, let's see... the day before doing the actual flush (olive oil, salts etc) was when i was doing the apples and juicing. i started the morning with some chamomile tea, then took some psyllium. from what i gather, it's not best to have eaten when you take psyllium. i can't give the exact explanation, but i think it's best on an empty stomach.
you can find psyllium at any health food stores. just ask and they'll lead you to it in their supplement section. i used one that was a multitasker. it also had clay in it, along with some herbs. you can just go with what feels right for you. i used to (and still do) just mix psyllium powder along with Bentonite clay. Also located in supplement section. There are recommended dosages on the package, if you've never taken it before it's best to start out little and work your way up. As far as how much in advance? well, psyllium is a good supplement as part of a daily regimen, so you can pretty much take it every day if you want. If you know you're headed into a cleanse/fast then you could up the dose and do it 2 times a day. Some people take it more, some less. I myself am going to do the Liver-Flush again in 2 weeks, so i'm going to continue doing the psyllium/bentonite, but like i said, it's a good thing to kinda always have going through you, so you can continue it for however long you want i would guess. i would think it's good to continue too, to help elminate any residue stones and toxins stuck in your colon in the following days.
The enemas i did the day of the flush and also the day after. It really doesn't matter when you do the one the day before. If i had thought of it, i would have done them MORE often in advance, maybe next time. The one the next day, I did when i thought i was pretty much all done with passing stones/and expelling. Even after my enema, i've still gone to the bathroom a few more times, and i've passed another dozen little stones. i don't like to do enemas when i know i've just eaten and food is digesting. then you're just messin with your digestion and absorbtion, so i like to do it in the morning, when i know i'm on empty.
i hope these things help, good luck with everything!