Hello,
In the Horizontal Pod Autoscaler documentation, the --horizontal-pod-autoscaler-initial-readiness-delay has an unclear definition and make comprehension very difficult:

Due to technical constraints, the HorizontalPodAutoscaler controller cannot exactly determine the first time a pod becomes ready when determining whether to set aside certain CPU metrics. Instead, it considers a Pod "not yet ready" if it's unready and transitioned to unready within a short, configurable window of time since it started. This value is configured with the --horizontal-pod-autoscaler-initial-readiness-delay flag, and its default is 30 seconds. Once a pod has become ready, it considers any transition to ready to be the first if it occurred within a longer, configurable time since it started. This value is configured with the --horizontal-pod-autoscaler-cpu-initialization-period flag, and its default is 5 minutes.

https://github.com/kubernetes/website/blob/master/content/en/docs/tasks/run-application/horizontal-pod-autoscale.md

• It doesn't specify how does it retrieves pods status. Is it with the readiness probe?
• What happen if the pods is ready before the end of the delay?
• Why not configuring the delay to 0 or 1 second?
• Is it affecting in any way the routing delay?

Thank you for clarifying