Final answer:
The nurse has not addressed the timing of referral correctly.
Step-by-step explanation:
The discharge planning action by the nurse that has not been addressed correctly is the timing of referral. The nurse in this scenario decides to make the referral on the day of discharge, which does not allow enough time for the referral process to be completed before the patient is transferred to the rehabilitation center. It is important for the nurse to make the referral in a timely manner, preferably well in advance, to ensure a smooth transition of care for the patient.