Customer first callbacks do not dispatch on time. How can I fix the issue?

To control the pace of dispatching callbacks, use the Pacing Modifier setting.

When you use this modifier, Genesys Cloud calculates a coefficient that is multiplied by the number of agents that are logged in to the queue to determine the number of callbacks initiated at one time. If you notice that your callbacks are not dispatching, you can either increase the pacing modifier under Admin > Queues > Callback, or you can increase the number of agents in the queue.