The file polling port will work great for this, but if you want to use a scheduler, then look at the services in pub.scheduler.
You will need two schedulers, the first is a one-time instance as per your description, the second will handle the 15 minute interval for file polling and is suspended. If you do not find the file, then turn on the second by resumeTask. Once the file is found, put it back asleep using the suspendTask.
I’m willing to bet that you can do the same with the file polling port if you research it. The file polling port should be able to be enabled via a scheduler and disabled once the file is found until the next time the scheduler is run.
Ray
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