Hi Gemma - long time, no speak! I don't come on minimins very often, and your post just caught my eye.
I'm a bit confused - easily done! If I've got this right, you've just finished your first week of SS, but now have to move up the plans? That's rather odd, so I thought I'd make it clear how Cambridge sole source works:
We need to be one stone heavier than BMI 25 before we can begin sole source. And we need to be on Step 2 (810) when we reach BMI 25.
It's sensible to move from SS to SS+ and then 810, in order to avoid that annoying water regain as much as possible.
All of this is in the booklets you will have received, but give your Consultant a call if you need any clarification.