Final answer:
Employees should begin assessing guests for intoxication after the first drink, which allows for proactive management of potential over-intoxication and ensures the safety of all.
Step-by-step explanation:
An employee should begin assessing guests for signs of intoxication starting after the first drink. This is because alcohol intoxication typically can begin after two or more drinks, and it is important for the safety of both the guest and those around them that potential over-intoxication is monitored from the start. Signs can include slurred speech, impaired coordination, and changes in behavior. The legal definition of intoxication often relates to a blood alcohol concentration (BAC) of greater than 5.4-17.4 mmol/L. Keeping an eye out from the first drink allows staff to manage the situation proactively rather than reactively and can help prevent situations where a guest may be a danger to themselves or others.