Reporting API 429 during JMeter load test on US1

Context:
Pushing 50 concurrent threads against /api/v2/analytics/conversations/summary on Genesys Cloud US1 via JMeter 5.6. Environment uses standard rate limits. The test triggers HTTP 429 Too Many Requests immediately after startup.

Question:
Does anyone know the specific burst capacity for this endpoint or how to configure JMeter timers to avoid hitting the limit?