After scheduling a job, how can I trigger it to run manually? (enqueue now)

I’ve used a ScheduleJob method, but I need a short delay before I cause the job to run (or else I’d use Enqueue). This is so that I can save the JobId on the relevant entity object. In the UI, I can then press the “Enqueue Now” button to cause it to run (almost) immediately. How can I do this in my own code? How can I Enqueue or manipulate a scheduled job?