CREATE TABLE table_203_478 (id DECIMAL, "week" DECIMAL, "date" TEXT, "opponent" TEXT, "result" TEXT, "attendance" DECIMAL)

which game date only had a bit more than 20,000 in attendance ?
SELECT "date" FROM table_203_478 WHERE "attendance" > 20000 ORDER BY "attendance" LIMIT 1
SELECT "date" FROM "table_203_478" WHERE "attendance" > 20000 ORDER BY "attendance" NULLS FIRST LIMIT 1