Hi,
Welcome. FOrgive the simplistic answer, but everyone is different. YOu have to look at a few factors. Male vs. female, amount of weight to loose, how much water you are drinking, how much you stick to it.
Initially, you might loose a lot more than you expected, but then after that first week or so, it might slow down. Read some stories adn you will see as mnay different versions as there are people. One thing that is consistent is that the people that stick with it see results and wonder why they didn't start sooner!
Good luck if you choose to go that route. You will do great if you do the preliminary work- read the book, make sure you are prepared, get whatever might tempt you away for a while.
I would highly reccommend popping back in here. Millions of scenarios play out and of course, you will most likely find someone whose life mirrors yours in one way or another.