Even if you don't face check... Foxfire > Spirit Rush > Charm > Orb of Deception > Spirit Rush > Spirit Rush > Foxfire and if they're still alive after all that, Orb of Deception one more time, while falling back/pursuing. If they've built magic resist and you're stupid enough NOT to have built magic pen, flash the wall and retreat. In total, your gank should take no more than the three-to-four seconds it takes for your Foxfire to cool down from its first casting.
On a non-tactics note... I'd face-check ANY bush Ahri was in, ifyouknowwhatImean