DPSing depends on your tank's cooldown rotation, your WHM's capabilities, and your group's overall comfort and health levels so every answer will be different. What I personally (try to) do is

Phase 1: DPS almost the whole time, dropping Cleric Stance only to heal Flatten + Triple Breath (only on the second one because our tank uses Sentinel for the first one) and Earthshaker. Succor on Megaflare is optional.
Phase 2: Adlo Flatten, Succor/Soil Megaflare/Rage, DPS the rest of the time.
Phase 3: DPS the whole time, dropping Cleric Stance only for a few seconds after Storm and Pain are out.
Phase 4: Near full time heal, DPS between Megaflare and Earthshaker.

If you use Eos, Rouse + Whispering Dawn after AoEs and Fey Covenent before Gigaflare.