That is important because Republicans get one shot to sink the Dem. If they fire too early, the press figures out how to spin and mitigate the damage. So they have to balance between not opening fire too late when it won't matter any more vs. opening fire too early when the damage can be cleaned up by the press. The next several weeks are going to be total war and unlike McCain, Romney is well prepared for it.
The last weeks will be a campaign the likes of which no one has seen before.