CREATE TABLE table_name_92 (podcast_date VARCHAR(255), run_time VARCHAR(255), episode_number VARCHAR(255), historical_references VARCHAR(255))
What is the date of the episode that is before 307, run time equals 5:48 and has P.T. Barnum as the topic?
    
SQL: SELECT podcast_date FROM table_name_92 WHERE episode_number < 307 AND historical_references = "p.t. barnum" AND run_time = "5:48"