Why didn't the members of the Godhead have to deliberate for a long time?
They did not need extended deliberation because all three persons are members of the Godhead. Their counsel was a meeting of minds, not a lengthy debate; from eternity past they agreed together and in that counseled agreement set everything in motion.
Les explains that because all three were members of the Godhead, they did not have to deliberate for a half an hour. Yet the Trinity still came together, counseled with one another, and in a counseled agreement set everything in motion. This counsel reaches back to eternity past, before anything was called into being, when there was still nothing. Peter, preaching on Pentecost in Acts 2:23, speaks of Christ being delivered by the determinate counsel and foreknowledge of God. Genesis 1:1 uses bara, meaning out of nothing. So when it was still nothing, the triune God counseled, agreed, and determined that they would create the universe and put one little planet like a speck in the midst of it.