[Answer]-Deleting conditional data from MySQL + Django

You might try writing a simple bash script and put it in cron which can do all the deletion magic using plain SQL queries.

mysql --host=localhost --user=user --password=password << END

DELETE FROM `table_name` WHERE `tm_field` >= 'YYYY-MM-dd HH:mm:ss'

END

Since SQL queries are light-wighted in comparison to ORMs and deleting data in smaller chuck/frequently can help you greatly.