Well, I think it's likely that some duration of abilities will increase and change as part of the class buff. I think Shadow Fang will likely be a longer duration than 18s at level 50, and until we know the timing, the only thing we can really be sure of is...

Is Storm's Path/Dancing Edge Debuff about to fall off? If Not Put it on.
Is Mutilate about to fall off? If not, put it on.
Is Shadow Fang about to fall off? If not, Put it on.
If above is all on, use Aeolian Edge Combo.