Tip the Scales is a self-buff that makes the next empower spell cast instantly at its maximum empower level. By itself it's a setup tool, not a healing cooldown, its raid value comes almost entirely from the Chronowarden hero tree.

With Chronoboon, the cooldown drops from 2 minutes to 90 seconds. With Temporal Burst, every cast applies a cooldown recovery rate buff that starts at 30% and decays to 0 over 30 seconds, averaging out to roughly 4.5 seconds of bonus cooldown progress per cast on everything recharging during that window.

With a cast every 90 seconds, that works out to about 3 seconds of extra cooldown progress per minute on each of the evoker's other cooldowns, which over the course of a fight quietly compresses the timers on Dream Flight, Rewind, Stasis, Zephyr, and Time Spiral.

Treat Tip the Scales as a healing amplification window. The Temporal Burst buff it triggers gives roughly 30 seconds of decaying haste, ramping the evoker's healing throughput for the duration, and the instant max-empower cast it enables (typically Dream Breath or Spiritbloom) adds an up-front burst.

Line the window up with a damage window when timing allows, but otherwise just cast it on cooldown. The cooldown recovery rate it also provides is a passive bonus on top, not the reason to press it.