What is the best time to take the usana essentials supplement? is it during day time or before going to bed? why night /day time?

Morning & afternoon: I advise taking 1 after breakfast & 1 after lunch, though might be ok to take 1 after dinner. Many of the ingredients (vit a, d, e etc.) are fat soluble so better absorbed after a meal. The b vitamins can be stimulating/energizing so some (not all) people might have a hard time falling asleep if taken too late in the day. Best to take 2 separate times as what you take in am won't be around in pm.