Literary criticism, analysis & review written in the centuries prior to the 19th is not indexed.
Works were reviewed and analysed in the 16th, 17th, and 18th centuries, and you can find that criticism.
Strategy #1 - Find a Comprehensive bibliography on the writer or school or topic.
One of the best ways is to find a comprehensive bibliography on your writer or topic. By this I mean a Book Length bibliography. If there is one, it will usually list all the earliest criticism published on that writer or topic.
To do this, search library catalogs for the writer or topic as SUBJECT and the word Bibliography in the TITLE.
However, all authors will not have one of these. Only the most famous writers will have one.
Strategy #2 - Find a Biography
Many authors who do not have a full length bibliography about the, do still have a biography written about them. A biography will often mention early criticism because how the writer felt about the criticism and reviews received effected that authors life, and so is part of the story. So, check the biography for references to the writers reception by the public and colleagues. It will usually then have a footnote or reference in the back to the full citation for the criticism.
To find a Biography - search for your Writer by SUBJECT, find one book on the writer, and jot down the starting call#. Biographies will be shelved after the actual works by the writer and before the criticism.
Strategy #3 - Find a Bibliographical Essay
Sometimes someone will write a bibliographical essay on your writer or topic. This means they will write a journal article, that discusses the earliest criticism and analysis of a writer or topic.
To find this type of article - Search The MLA Bibliography for your writer or topic as SUBJECT and the words Bibliograp* OR "early criticism" in the TITLE field.
Strategy #4 - Ask a Librarian
If none of these strategies work, please email me, Sharon at sclayton@knox.edu, and let me know your paper topic. I should be able to help you identify some sources.