availabilityStartTime

AvailabilityStartTime is a timestamp that marks the beginning of a defined availability window for a resource, service, or person. It indicates when the resource becomes available for booking, assignment, or use, and is commonly paired with an availabilityEndTime to define a complete time span.

In data models and APIs, availabilityStartTime is typically stored as a date-time value in ISO 8601 format with a time zone or as UTC. It may be returned as a string, such as 2025-07-14T09:00:00Z, or as epoch milliseconds. When used, it is important to consider time zone handling and display, often converting to the user’s local time for presentation.

Common use cases include scheduling systems, appointment booking, workforce management, room or equipment reservations, and service provisioning. AvailabilityStartTime helps determine when a resource can begin fulfilling a request and is essential for aligning with availabilityEndTime, duration, or recurrence rules.

Constraints and validation typically require that availabilityStartTime precedes availabilityEndTime, and that the window aligns with business hours or resource constraints. Applications should validate inputs, manage time zone conversions, and accommodate daylight saving changes. For recurring schedules, start times may be defined in relation to a recurrence rule rather than as a single fixed timestamp.

Implementation considerations include efficient querying for time-based ranges (indexing on the start time), ensuring data consistency between start and end times, and handling various display formats for end users. Related concepts include availabilityEndTime, availabilityWindow, and time slot representations.