Find out date and or number of error logs xp_readerrorlog
If you run EXEC sys.sp_enumerrorlogs; it will return one row for each log file, the oldest date in the log file, and the log file size.

Which means you can do something like this:

CREATE TABLE #error_log
(
    log_number INT,
    log_date DATE,
    log_size INT
);
INSERT #error_log ( log_number, log_date, log_size )
EXEC ( 'EXEC sys.sp_enumerrorlogs;' );

SELECT *
FROM   #error_log AS el;


Then set up a loop to grab the max log number, only grab logs after a certain date, or perhaps exclude logs based on size. Some small logs may be uninteresting, and some large logs may take too long to process.