You can currently start right from the beginning without playing any of the other books. Download the most recent version, go through the intro and click on the black part of the yin/yang symbol to start the slave epilogue. MITY/Marty has implied that there will be some different dialogue if you do B4S first, but I didn't immediately notice any on my playthroughs. I do need to start a fresh save though, as I mentioned a few days ago I ran into an error, and I wouldn't be surprised to find out my save was bugged from the back end changes MITY made and a save from an older edition.