Time Warp & Icy Veins usage

Hello, I have a questing about these cooldowns. Let’s say you’re about to start a boss fight, and you use your Time Warp which gives 30% haste. Do you wait until it has ended before you use your Icy Veins 20% haste cooldown?

Together, always.

Though be mindful of where your group wants Time Warp to be used.