Really really hard to tell. Let me say a few things:
After your body switches to ketones, a good approximation is 4000 kcal per pound of fat. So it depends on how long it takes your body to switch to ketones, how active you are and your metabolic rate.
Total weight loss will depend a lot on your eating and exercising right before starting the fast. If you are coming out of a week of eating and drinking with no exercise, I wouldn’t be surprised if you lost 10 lbs in the first two or three days. But that’s all water weight that you were retaining.