I've not hugely theorycrafted the optimal pot timing but what SEEMS to be best to me from smoothness is something like:

Fast Blade -> FoF -> Riot Blade -> STR Pot -> Goring Blade -> Circle of Scorn -> Royal Authority Combo x 2 -> Goring Blade Combo

You can fit in a Spirits Within and Shield Swipe whilst the Str Pot is running, and the STR pot should buff the Goring Blade DoT and one full Royal combo.

At higher Skill Speed though I have no idea, as it makes more sense to pop FoF before the Goring Blade and then pop the Strength pot about halfway through the FoF so it buffs the -second- Goring Blade.