Simplot has a booklet, Origins of the JR Simplot Company that highlights 1909-1955. It looks like they used a continuously running conveyor belt fryer in early 1953 and mentioned modest success in selling frozen fries at the retail level, although he felt the potential for the product was greater at the institutional level.  The booklet has a 1953 billboard showing family style 1 pound crinkle cut French fried potatoes with the by line: “with the successful start-up of a continuous French fry production process in 1953, the company began marketing institutional and retail frozen potato products.”

In another section it says  “Although the institutional market was clearly the focus for sales by the mid-1950’s, the company’s movement of frozen French fries was equally divided between the retail and industrial markets as late as 1958.”

From what I can tell, you’d have to beat their 1953 start on the fries for retail.