1-2 pounds per week is a realistic goal. Really rapid losses will tend to include muscle loss. Muscle is a calorie burner and will cause stalling later. The more rapid your weight loss the harder it is to maintain later.
That said, the first month is both the easiest and the most difficult. It is easy to stay on plan as your motivation is high and you are seeing losses. It is difficult because you have to relearn how it feels to be hungry and not over stuffed plus there are many times where food is very tempting.
As you progress the plan can become routine. You start to know how much food is enough the problem happens when you stop measuring, stop recording and try adding little treats and tastes. Life starts to get in the way and motivation decreases.
We are all really trying to relearn how our relationship with food and eating. So really focusing on your eating triggers now can help later. I have learned that I eat when I am angry and frustrated and if I eat certain foods I tend to not be able to stop myself from having more. Pasta, bread and my boss are huge triggers! My hope is knowing my triggers will lend to maintiaining my weight loss later.
In for the long haul!