There's no real sense in waiting I think, I just use Unchained to boost the damage/enmity of my initial OPs while I start rolling offensive CDs + Bloodbath and then go into Deliverance. If Unchained isn't available I eat the penalty, but it also lets me sit on my 5 Abandon stacks for a bit for the crit bonus. I suppose I would wait a bit longer on Unchained if my healer didn't feel comfortable with me swapping that early, but Defiance doesn't really do anything if my healer isn't healing me and the healer I run with is usually too busy DPSing to be doing that. :P
