Hi
The first two days were a bit ropey for me, and as mentioned above try to cut down on your carbs for at least 3-4 days before hand, as this stops the withdrawal from carbs being quite so bad.
I would also buy in 2-3 extra packs. I know SS it should be 3 packs a day, but I found for the first 3 days the thought that i had an extra pack if things got too bad to bear was quite comforting, I think I used one. Better an extra CD pack than something that will set you back to square one.
Also try to keep occupied.
Drink your water
Add a wee bit extra water to your shakes, I like mines thinner/bigger so add 500 ml
(plus if you do this you could technically have 6 1/2 portions throughout the day if you'd find it easier)
Hang in there, everybody differs but generally after the first 3 days you'll find it a lot easier.
Try not to cheat (I speak from experience here) it means that you will bet your progress back a bit and ultimately be o SS for longer.
Most of all though, come on here for support, the support of people who are on CD is very important, as "outsiders" will give you grief about your "unhealthy faddy diet" and it can get a bit wearing after a while.
GOOD LUCK