Earliest Start Permitted and Due Date is the appropriate Field Service design. These fields define the internal scheduling window that represents when the appointment may begin and the latest time by which it should be completed. They are the Service Appointment fields most directly aligned with SLA constraints.
Operationally, the goal is to preserve schedule integrity while minimizing manual intervention. Field Service should be allowed to use the standard scheduling engine wherever possible so that resource availability, travel, appointment constraints, priorities, and territory context remain consistent across manual and automated scheduling actions.
The alternatives address different parts of the Field Service model. Scheduled Start/End are scheduling outcomes, Actual Start/End record execution, and Arrival Windows are customer-facing arrival expectations rather than the core SLA boundaries.
This approach keeps the implementation aligned with the standard Field Service data model and avoids unnecessary customization. Study Guide reference: Managing Scheduling and Optimization - Service Appointment constraints; Earliest Start Permitted; Due Date.