CREATE TABLE table_204_881 (id DECIMAL, "round" DECIMAL, "date" TEXT, "score" TEXT, "opponent" TEXT, "opponent's score" TEXT, "result" TEXT, "venue" TEXT, "attendance" DECIMAL, "best on ground" TEXT, "team" TEXT)

which venue was the first to have over 30,000 attendees
SELECT "venue" FROM table_204_881 WHERE "attendance" > 30000 ORDER BY "date" LIMIT 1
SELECT "venue" FROM "table_204_881" WHERE "attendance" > 30000 ORDER BY "date" NULLS FIRST LIMIT 1