Hi Vicky and
I'm not going to suggest a timeline for you but I know a few places on this site that might be able to help.
If you go to the support groups section you could have a look at the 300+ club or the 100lb club. Those gals really know what they're talking about. Also check out the UK fat chicks forum which is the next one down after introductions.
Take a good long look around the site and read and post loads - you'll soon find where you're most comfortable and well done on losing a stone and a half so far!