Eventually anyhow. I assume the OP wants to not use WM at first, so that they remain mobile and can get it up a lil faster and then ease into WM once the fight 'stabilizes?'

Anyhow, there really isn't much reason to not have WM active at fight start. I mean we can get into debates about DPS and stance dancing.. but in the end.. its not really going to matter unless your team is 'that' close to barely making a dps check.