Answer for When is the best time to take the Keto O/S?

Anything over 50 calories or so will break your fast.  So you would do about 1/3 of a serving before workout and not break your fast. 
If your goal is weight loss, then it is best to work out in a fasted state.  That will make your body use the most endogenous ketones (generated from your fat cells).  If you supply exogenous (keto OS) ketones it will use those for energy instead of your fat cells. 
Another way to use Keto OS for weight loss is to extend your fast.  If you get hungry or have craving before your fast is up, take 1/3 packet to extend your fast. You can also do this to enhance your fasting by making the eating window smaller (say 6 hours or even less).