My reason in asking was very well explained by others- prior finds did not net the same reaction that this one did, according to what we heard.
If it is true that the find in the little econ was met with little reaction or concern while the find at Suburban was met with such a reaction- and a need for sedatives, before it was even confirmed that this body was that of a little girl, let alone that it was Caylee, it is clear that Casey knew that act 1 of her little play was over.
I agree with your assessment, pirate. Casey KNEW it was Caylee's body that had been found. Her reation was one of surprise and not a planned performance on her part.
So, yes, she immediately knew Act 1 was over.