What is a Timer Start Event in BPMN?

A Timer Start Event automatically creates a new process instance based on a time condition—at a specific date/time, after a duration, or on a recurring schedule. It is represented by a thin circle with a clock icon.

When should I use a Timer Start Event?

Use Timer Start Events for processes that should run on a schedule without manual intervention—daily reports, monthly billing cycles, nightly maintenance jobs, or any workflow triggered by time rather than a user or system action.

How is the Timer Start Event different from related elements?

Timer Start Events begin a new process instance, while Timer Intermediate Catch Events pause an already-running process until a time condition is met. A plain Start Event requires an explicit trigger rather than a scheduled time.

eventstimer triggerVariant of Start Event

Timer Start Event

A Timer Start Event launches a process automatically at a scheduled time, after a delay, or on a recurring cycle. It eliminates manual triggers for time-driven workflows like daily reports, monthly billing, or periodic maintenance tasks. For example, a payroll process uses a timer start event set to "every last Friday of the month at 9 AM" to automatically begin salary calculations.

What is a Timer Start Event?

A Timer Start Event automatically starts a new process instance based on a time condition. It can fire at a specific date/time, after a defined duration, or on a recurring schedule using ISO 8601 timer expressions (e.g., cron-like cycles).

Visual Representation

The Timer Start Event is shown as a thin circle (indicating a start event) containing a clock icon. The clock symbol distinguishes it from other start events and signals that the process is triggered by time rather than a message, signal, or manual action.

Key Characteristics

Three timer types: Supports specific date (timeDate), duration (timeDuration), and recurring cycle (timeCycle) expressions
Automatic instantiation: Creates new process instances without user or system interaction
ISO 8601 expressions: Uses standardized time notation for portability across BPMN engines
Top-level processes only: Cannot be used inside sub-processes; use Timer Intermediate Catch Events for mid-process delays

See it in action

SpaceZ's production cycle starts at the beginning of each quarter

Read: The Space Ship →

Common mistake

Using a timer start event inside a sub-process. Timer starts can only be used at the top level of a process.

How it connects

Timer CatchTimer Start Events create new instances on schedule; Timer Intermediate Catch Events pause a running process StartPlain Start Events require manual triggers; Timer Start Events trigger automatically on schedule Conditional StartConditional Start Events react to data changes; Timer Start Events react to time/schedule Message StartMessage Start Events need an external message; Timer Start Events fire autonomously on a clock

Common Use Cases

Scheduled Report Generation

A daily or weekly reporting process starts automatically at a set time to compile data, generate reports, and distribute them to stakeholders.

Recurring Billing Cycle

A monthly billing process is triggered on the first of each month to calculate charges, generate invoices, and initiate payment collection.

Periodic System Maintenance

A nightly maintenance process starts at off-peak hours to perform database cleanup, cache invalidation, and health checks.

Frequently Asked Questions

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