Kubernetes CronJob, don't queue up missed jobs

I've read these docs over multiple times but still don't think I understand what startingDeadlineSeconds does.

I'm trying to figure out if it's possible to avoid rescheduling a job if a current one is running (with CronJob) and instead just let the next scheduled job pick up where it left off.

I have some extremely erratic job completion times (a separate problem I need to solve). It may take 1 hour or up to 24. So sometimes, if a Job takes a whole day to complete, but I've scheduled it to run every 12 hours, I get a queue of another job that immediately starts when the last one is complete.

I'd really just like it to never queue up a job and only create new jobs on the next scheduled time.

Here's a sample of the config

apiVersion: batch/v1beta1
kind: CronJob
metadata:
  name: my-job
spec:
  schedule: "0 */2 * * *"
  concurrencyPolicy: Forbid
  successfulJobsHistoryLimit: 1
  jobTemplate:
    spec:
      backoffLimit: 1
      template:
        spec:
          containers:
          - name: my-job
            image: my-image
            command: ["do_something"]
          restartPolicy: OnFailure

Note that do_somethign could take 1 hour, or it could take 4 hours. What I'd like, is when it takes 4 hours, to not have queued up the 2nd job that would have normally run if it had taken less.

Is this possible with Kubernetes CronJob?