The southern states knew what the Republican plans were as soon as their nominating convention was over.
"But regardless, your claim was secession occurred because Lincoln and the Republicans were waging economic war on the Southern states. Since, as I said, they didn't control the White House and Congress until after secession then how were they able to wage the economic war that led the Southern states to rebel?"
There were Republicans in Congress well before this specific election, as well as "proto-Republicans" (Whigs and others) who had been pushing the same agenda. The only thing that the election did was show that the proposed economic plan was inevitable.
So in other words there was no "economic war" being waged when the Southern states began their rebellion. Nice to know.