Final answer:
When another agent is already showing a property, you've arrived at, the best practice is to wait for them to finish before starting your showing. Informing your buyers about the situation is also considered professional etiquette.
Step-by-step explanation:
When arriving at a property for a showing, if another agent is showing the property, the professional course of action would be to wait for them to finish. This shows respect for the other agent's time with their client and ensures that you are not interrupting their showing, which could be disturbing or distracting.
It is also considered polite to inform your buyers of the presence of another agent to set the proper expectations. This can help maintain a flow of courtesy and professional ethics within the real estate community. After the other agent has finished, you and your buyers will be able to view the property in private and discuss matters freely without the potential pressure or awkwardness of another party being present.