There were no tariffs on exports only imports. The self imposed blockade of cotton from the South to Europe did not work and was a very poorly conceived idea by the agents of the Southern cotton trade, the Confederate government never officially authorized an embargo act with Europe only the North. The embargo of cotton to Europe was threatened as far back as Nov-Dec. 1860 and was in practice by June 61, so I believe the cotton trade was cut before the shooting began. Recognition was not the only reason, it was felt early on, that any cotton trade with Europe would result with that cotton ending up in Massachusetts anyway, and the South wanted to hurt the North more.
With your idea, the individual states could not have implemented prior to secession, and it would have had to come from the individual planters, actually cotton agents, and I doubt they would have joined together to reduce their profits.