On a bus where the aisle is lower than the seats, when is the best time for the driver to warn riders about the step-down?

49 CFR 383.117(a)(6) (operating practices not otherwise specified); AAMVA CDL Manual Section 4.2.4 "At Your Destination," p. 4-2

Riders gathering their things and heading for the door are the most common bus-related injury: a trip-and-fall on an unexpected step. Timing the warning before the full stop, while riders are still paying attention to the driver's voice, is a small detail the exam uses to test real operational understanding, not just rule memorization.