This is likely not a realistic goal. You’re two days into IF and calorie reduction. Until you’ve been doing this for a month you really have no idea how sustainable it is for you.
To drop 200 pounds in 10 months requires a sustained caloric deficit of about 2,400 per day. That’s extremely difficult. A deficit of 1,000 to 1,500 per day is more realistic given where you’re starting. I would recommend sustaining a 1,000 calorie per day deficit for 2 weeks. If it feels like you can do more, then bump to 1,500 and sustain it. You’re always free to adjust as time goes on and you learn more about what you can and cannot do.
My recommendation is to focus on what you can control. Get attached to the process of IF and eating properly in your windows and don’t focus on the scale. Celebrate the success of completing a fast and celebrate just as much the completion of an eating window where you stay on plan. The weight loss will come. That’s just a side effect of your new lifestyle though.
It’s a bad idea to lose weight that fast but if that’s what you wanna do then go for it! You could maybe start at a 1000 calories but if you’re feeling weak definitely increase your calories a bit and see how your body responds, good luck!
Since you’re starting weight is high you could lose higher amount of pounds in a shorter amount of time. 1000 feels a bit low so up that a bit in order to still receive your daily required nutritional intake imo. I would just work on the diet end and not throw in exercise until you are a bit lighter. Your joints would like that a bit more at this stage.