Start jenkins job immediately after creation by seed job
You can use queue DSL command to schedule a build, see https://github.com/jenkinsci/job-dsl-plugin/wiki/Job-DSL-Commands#queue.
To queue the job only if it's new, you need to use the Jenkins API to test if the job already exists.
if (!jenkins.model.Jenkins.instance.getItemByFullName('my-job')) { queue('my-job')}