User blog comment:CoolJazzman/What I think will happen./@comment-7677067-20130720113740/@comment-11051098-20130720205515

I also understood from what Yhwach said to Haschwalt when they prepared to leave before Ichigo showed up, that one of Yhwach's main goals was to draw out the Royal Guard. But they definitely didn't intend to capture anyone then.

Like you said, kill Yamajii, steal Bankais, recruit Aizen, and finally draw out the RG.

Speaking of the RG, I think they could have killed alot of Stern Ritters if they showed up earlier. But they probably didn't want, or were allowed, to go to the Seireitei before the enemy had departed. If they did, and left the Soul King unprotected, maybe Yhwach could have attempted to invade the Soul King Palace dimension to kill him/it.