This might be a bit controversial but...
I would wait to start until you are in a position to start. I think the point where you go to the first meeting, get weighed, and then start out on your new journey is a very significant one, and it gives you a great deal of focus to actually be there and go through that.
Also, I lost 2 1/2 stone before I decided to join, by myself, and I always regretted not having started SW at the very start - not that a 5 stone award is by any stretch of the imagination to be sniffed at, but it could have been a 7 1/2 stone award and a more complete journey.
This is just my opinion mind, if you are set on getting started now then great, loads of hints and tips on here.