Can you elaborate? When running on HDP the default is Capacity Scheduler as opposed to Cloudera whose default is fair scheduler.
Fair scheduling is a method of assigning resources to applications such that all apps get, on average, an equal share of resources over time".
Furthermore, Fair Scheduling doesn't mean that submitted application will get required shared of resources right away. If the application is submitted to a busy cluster and requested resources cannot be assigned it will have to wait until other applications finish, or resources are freed using preemption mechanism (if enabled).
So an answer to your question would be YES it's instant if you have enabled pre-emption in CDH !
Hope that answers your question if you need more precise answer please elaborate.