Final answer:
Fetal engagement in primigravidas typically occurs around 2 weeks before the due date, signaling readiness for labor.
Step-by-step explanation:
The perinatal nurse is educating first-time parents on the process of fetal engagement, which refers to the baby's head descending into the mother's pelvis as a preparation for birth. In primigravidas, women who are pregnant for the first time, fetal engagement typically occurs around 2 weeks before the due date. It is an important milestone as it indicates readiness for labor though the actual timing can vary from one individual to another.