CREATE TABLE table_29520 ("No. in series" FLOAT, "No. in season" FLOAT, "Title" TEXT, "Directed by" TEXT, "Written by" TEXT, "Original air date" TEXT, "U.S. viewers  ( millions ) " TEXT)

List the 1st air date for season 12.
SELECT "Original air date" FROM table_29520 WHERE "No. in season" = '12'
SELECT "Original air date" FROM "table_29520" WHERE "No. in season" = '12'