I'd suggest that if you think you want to lose 2 stone, then a large proportion of that will be your glycogen and liquid stores (it varies a lot from person to person, but could be 5-7lb maybe?), which you'll lose in the first week. After that, while you're properly using up fat, it might be 2 or 3 lb a week.
With a bit of luck you could lose 2 stone in 2 months, but be prepared for it to take 3 or more. Like I say, it varies a lot!
Try not to get thinking too much about how long it will take. You could lose that 2 stone in 6 weeks but if thats all you are losing then after those 6 weeks you will have to be very careful and follow the re-feed and maintenance plans for a while otherwise a stone could just go back on very quickly.
Good luck hun and you need to make sure you are drinking 2 or more litres of water a day x