The first two or three days will probably be a bit nasty as the carb withdrawal symptoms hit - to make it easier, it would help to reduce carbs (especially sugar), and caffeine in the next few days, as that will give you a more steady reduction. From my past experience, it's very tempting to have a last bad food binge (or 5!) but that will only make the experience of the first week worse. Looks like you're already doing well on SW, so I'd maybe do some red days to make the transition easier - Good Luck!