If the content is ready, I see no reason to delay it. The world first race is such a minor thing that just lasts for 3 days...and if you really want to run it min iLvl, you still can do it later.
If the queues are still as bad when savage comes out, 'til which date do you want it postponed? When they do the server upgrade? 6.1 or maybe even later? And then you won't have enough time to get your BiS for the Ultimate? And if Ultimate also gets postponed because of it, ultimate raiders will be mad.