During job interviews, on first dates, and when meeting new
coworkers, people make assessments of one another very quickly.
It may seem odd that "first" (which usually refers to only one thing) is used with the plural "dates". While a person may only have one "first date" with any single person, they may have many "first dates" each with a different person (one first date with person A, one first date with person B, etc.). The statement in the example sentence applies to any first date with any person, so it applies to "first dates" in general.
The phrasing of "first dates" also fits with the parallel rule. job interviews is plural. first dates is plural. new coworkers is plural. Everything is plural; everything is parallel.