Are any of the Antiviral Regimen supplements best taken on an empty stomach to be most effective?

This is not the case, and if you think about the fact these are phytonutrients and intended through divine design to be a normal part of human diet, it would be customary that when ingested directly from nature it would be in conjunction with the intake of other foodstuffs, even when added as a medicinal step and not normally ingested for its taste.