Answer for Intermittent Fasting

Well, the bullet proof coffee would have to be in your eating window (12pm to 7PM). As for keto OS, as long at total calories are below 50 you will maintain your fast so you can use 1/3 packet outside the eating window to extend your fast (weight longer to eat, curb cravings when they hit, etc).
As for the plan, 7-12PM is late and a bit wide. 12PM would only result in a 12 hour fasting period which wouldn’t give you the effects.  You start to see the real effects of fasting after 14-16 hours.  That is why we like a 6 hour eating window.  But 8 is ok too.  Also, make sure to stop eating at least 3 hours before bed.  Otherwise you mess with your HGH production at night and will limit your weight loss.