CREATE TABLE table_8219 ("Office" TEXT, "Type" TEXT, "Location" TEXT, "Took Office" TEXT, "Left Office" TEXT)

What date did the executive office in Dover take office?
SELECT "Took Office" FROM table_8219 WHERE "Location" = 'dover' AND "Type" = 'executive'
SELECT "Took Office" FROM "table_8219" WHERE "Location" = 'dover' AND "Type" = 'executive'