MLA style aims to make in-text citations as unobtrusive as possible, so we normally recommend placing them at the end of a sentence, but sometimes for clarity you may need to insert a citation earlier–for instance, when the number of quotations in your sentence exceeds the number of page numbers:

Rather than a suspicious reader’s “digging down” or a surface reader’s “standing back” (52), she would like to see readers “forging links between things that were previously unconnected” and thus “creating something new” (173, 174).* 

You might also need to insert a citation earlier when you are quoting from one source but paraphrasing from another:

The call to distant reading, the demand for “macroanalysis” (Jockers), has been accompanied by a manifesto for surface reading, an insistence that we say goodbye to all that symptomatic root-canal work on rotten ideology in the text and that we eschew comparatist master narratives; surface reading’s textual description may include book history or distant reading (Best and Marcus 17).

You might insert a citation earlier as well when you want to emphasize that what follows the quotation is your own idea:

If there was ever a time for “styles of suspicious reading that blend interpretation with moral judgment” (86), it’s now.

*The first and third examples are taken from Diana Fuss; “But What about Love?” PMLA, vol. 132, no. 2, 2017, pp. 352–55. The second example is taken from Alison Booth; “Mid-Range Reading: Not a Manifesto”; PMLA, vol. 132, no. 3, 2017, pp. 620–27.