I set a realistic goal of 150 for myself. My weight in high school was between 130-145. I figure since i'm a bit older, it would be hard to reach and maintain those weights now. I have a large frame, so 150 is right at the end of healthy BMI. I'll see how I look and feel when I reach that point. If I feel like losing a little more weight will look and feel better, I'll work on 10 pounds at a time.
Weight loss is one of the things where I'm not in favor of adding a date to the goal.
It's so hard to predict how much your body will lose over time as there's so many factors involved. Many people get discouraged when they don't lose x amount by x date.
I like to just stick to the weight loss goals on the scale and not on the calendar.