He drafted three orders for Lincoln’s signature. None of which gives him direction to unilaterally start shooting.
Since we've never seen a copy of these orders, how do you know they didn't give him authority to start shooting?
Especially given the fact that when he got to Pensacola, he was indeed intending to start shooting, and only stopped with much disgruntlement, because Meigs had blocked his path with another ship.
As time went on, he did open fire on a confederate ship, and then lob a shell onto the confederate docks.
Why would he open fire on them unless he was trying to start a war?