The answer to your question would be that the selected sentence would be as follows: The entry level position will be available in mid-July.
You should hyphenate the words in this case because here <em>mid</em> functions as a prefix. The fact is that usually a prefix like <em>mid </em> is joined and closed up with the main word (midterm). Yet, in the case of numbers and most proper nouns, <em>mid </em> is hyphenated.
