Would it be reasonable to assume that local commanders were preparing to get underway based on maybe flash messages or even media reports? That their instincts and training told him that “go time” was imminent?
I'm not military; thus, I don't speak from experience.
But I believe it is reasonable to assume that local commanders would a.) be aware of what was happening in Benghazi and b.) would take steps to respond, then c.) await the appropriate orders.