Throughout this week, especially during GA's testimony, I read/heard from various blogs, that 6 weeks ago they found out that George would be accused of molesting Casey.
I believe this is when they also found out that Zanny was a lie and Caylee supposedly drowned. I believe George and Cindy didn't know until opening statements, that Casey blamed them. Cindy's fault because she left the ladder up on the pool and George was watching Caylee before Casey got up in the morning. Once George and Casey realized Cayley was missing, George found Caylee and blamed Casey for her drowning and forced Casey to go along with his cover up plan.
Of course, it's not true, but the jury doesn't know as much as we know about the case.
It was when they found out everything was a lie and Caylee died that day. (they may have realized she was murdered that day by Casey.)