Suppose it depends. I've lost over 3 stone in the same time frame, about 11 weeks. Although I started lighter and have been adding exercise most days. I think it's all down to each person to be honest
The blurb says a stone a month but lots of people lose more than that especially in the first month, and some a bit less. Last time I did a VLCD I lost over 3st in 9 weeks, but that was combined with really intensive training for a half marathon, which I did the week after I re-fed! Good luck - if you stick with it you'll see great results really quickly, so it's good for impatient control freaks like me.
Firstly well done on your loss so far, you've done brilliantly!
i think you just have to take the plunge and go for it, I think you should work on the fact that if you do it for a month you could be 11st 7lb, just imagine how bloody good you'd feel then
Do whatever it takes to get you through the first few days, grab all the sleep you can if that helps - getting into the 11's is doable in no time for you, keep at it and you'll soon be there x