This might in reference to the nearest neighbors hearing 2 gunshots around 12:30 and the 911 call coming in a few minutes before 1:00. This would seem to indicate it took 25 minutes.
Of course, this is if you place a lot of belief in the neighbors stating they heard the shots at 12:30. In the last week or so, I'm starting to doubt that part of the timeline. IOW, the only timeline I'm comfortable with is from the 911 call onward. According to the witness, they looked at their clock at the time of the gun shots and stated it was 12:37 and LE told them their clock was 7 minutes fast. What if, in all the confusion, it was actually 7 minutes SLOW. (It wouldn't be the first mistake the media has made in reporting.) That would put the call at about quarter to one. If the killer(s) shot James early on and Jayme was the target, why stay 25-30 minutes, when they could be out and gone in 5-10 minutes? But then, I'm trying to apply logic to situation that doesn't appear to have much logic involved.