Combat on Zor'lok, I assume you have no daggers? Killing spree on cooldown pretty much unless you know your raid team can't push first echo after 1 force and verve. Also save it so you have it straight away for P2.
This is assuming you are talking about hc, otherwise it's a doddle.
On cooldown, when it's smart to. Be very careful on Attenuation platform and only use it just after an Attenuation. Also try not to use it just before he casts Exhale, as you could get targeted and do no damage or even kill someone. Every time I'm Converted it's usually seconds before KS comes off cd and the MC uses it though.