Hey there wild mustang. My advice is to not feel sick to your stomach. :) You have prepared well at least for the day before your fast and that should help you ease into it well. With any luck on a 4-7 day fast you will not experience anything too drastic.
Just be open to what experiences await. Many say to rest a lot but some suggest at least light exercise, a little walking or whatever. The main thing is just to respond to your body's needs. You are teaching it a wonderful new way of healing and it will certainly appreciate the effort. :)