LERNt was a study of brief education with naloxone distribution that found 5-10 minutes of education was sufficient for people who use opioids to recognize and respond to overdose events.
Behar E, Santos GM, Wheeler E, Rowe C, Coffin PO. Brief overdose education is sufficient for naloxone distribution to opioid users. Drug Alcohol Depend. 2015 Mar 1;148:209-12.