DAYTONA BEACH - The new Trader Joe's distribution center on the east side of Interstate 95 has been given the green light from the city to begin operation.How much of the three-building complex is now in use and how many of its expected 450 jobs have been filled remains somewhat of a mystery.Both Trader Joe's and World Class Distribution Inc., the company that operates distribution centers across the country for the upscale grocery store chain, are privately held and rarely speak to the media. The two companies share some of the same top executives, according to state incorporation records filed in California and Florida.