Realistic loss per month?

So, for those of us who started with at least 100 lbs to lose or more, what do you think is a realistic weight loss goal for the first month?

To give you a bit more info, I'm not doing anything drastic, just getting started. I'm doing 20 minutes of Zumba a day and planning to increase or change the workout each week. As for diet, just trying to stay within my calories and get used to that for now.

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