CREATE TABLE table_2588 ("No. in series" FLOAT, "No. in season" FLOAT, "Title" TEXT, "Directed by" TEXT, "Written by" TEXT, "Original air date" TEXT, "Production code" TEXT)

When did the episode titled 'Route 666 (part 1)' air for the first time?
SELECT "Original air date" FROM table_2588 WHERE "Title" = 'Route 666 (Part 1)'
SELECT "Original air date" FROM "table_2588" WHERE "Title" = 'Route 666 (Part 1)'