I'm not sure about your chronology. Wayne Smith, an American diplomat posted in Cuba, wrote in his book The Closest of Enemies:
Blow followed blow. On June 7, 1960, Esso, Texaco, and the British oil company Shell, refused to refine Soviet crude oil imported by the Cuban government. Cuba responded on June 28 by nationalizing all three foreign refineries. The U.S. Congress, in turn, on July 3 authorized the termination of Cuba's sugar quota, and on July 6 President Eisenhower, acting on that authorization, announced that the U.S. would not buy the 700,000 tons of Cuban sugar remaining in the 1960 quota. Cuba retaliated by nationalizing all U.S.-owned industrial and agrarian enterprises on August 6 and all U.S.-owned banks on September 17.