There is no reason not to use quelling if you have it, at start of boss in your opener. it's basically a 15 sec window for tank to establish hate before im coming out the gate. use on cd or, depending on fight, save if there's new mobs or whatever about to appear and tank's starting aggro from scratch again on those.

having said that, seems to be getting more frequent that im taking hate even thru quelling anyway, idk what some tanks are doing