Possible in Jenkins to add sleep time between build actions?

There is a built-in feature in Jenkins to put a sleep but it is not easy to find it because they call it differently.

On the following screenshot

You can see there is a Quiet period setting in the advanced project options that is "executed" before the current job (project).

If you have 3 jobs you can as well set this setting for jobs 2 and 3 which will make:

job1 -> (sleep -> job2) -> (sleep -> job3)

If you mean to know how to sleep between those build steps you can use sleep with Execute shell type.

sleep 30s

You can add sleep command (on Unix) in the test build action before test execution.

It is possible to use sleep step in your Jenkins Pipeline. The step is included in Pipeline: Basic Steps.

Example:

steps {
  sleep time: 250, unit: 'MILLISECONDS'
}