That's what I was thinking! CC worked nights (which still strikes me as odd based on his position, but anyhoo) and if the letter-writing killer was actually targeting Sheri and the boys, they would have had plenty of perfect opportunities to commit the murders while CC was at work. Makes no sense...
I do tend to believe CC was somehow pushed into the final phase of his plan ahead of schedule for some reason. However, I am still waiting to hear if he was supposed to be at work the night before and if they were truly planning to separate or divorce. I would also like to know when he normally went to the gym...
I'm thinking he had to force the timeline in the morning because Sheri and the boys were expected elsewhere soon and people would have noticed they were not where they were supposed to be.
....like school? Wasn't it a school day?