Build the evening as one movement.
Treating dinner, nightlife and the return as unrelated transfers creates unnecessary gaps. A better brief maps the confirmed sequence and the expected decision points between locations.
This is especially useful when several guests may leave at different times or when a second vehicle could become necessary.
Agree the communication line.
The principal, assistant and driver should not all need to manage separate operational threads. Decide who can change timing and who should receive movement updates.
A clear communication structure matters more after midnight, when plans tend to move quickly.
Define the pickup logic.
For each major stop, clarify the planned pickup point and the fallback if access, traffic or venue operations make that point impractical.
The goal is not to over-script the night. It is to remove avoidable confusion when the group is ready to move.
Plan for split departures.
Groups do not always return together. If that is likely, the brief should make clear whether the vehicle remains with the principal, whether another vehicle can be requested and how the remaining guests will be handled.
Those decisions are easier before the evening begins than at the end of it.