Hope you're weigh in goes well! I had mine last night, 8lbs in the first week! Not too shabby. You should definitely shift some weight in the first week - be it water weight or otherwise!
Agree with you on the chocolate milkshake. Strawberry is good also! Haven't tried the porridge - just been on shakes, apart from yesterday I tried the spicy soup. Which surprised me, it was actually really good! I added a bit of extra hot chilli powder just to mask any potential powdery taste that I'd been warned of but it was all good!
I would make sure you have your shake, even if you're not hungry. There's nutrients and vitamins etc in there that you'll need. I found it difficult timing things with being out over the weekend - I usually try and leave 4 hours between each product/meal, but even when I don't, I don't really get hungry.