Do you know cronjobs? That is a great thing to schedule and let run tasks only once or repeatedly. This comes with every linux. And as you know OS X is based on a BSD. So, you have that functionality on your Mac, too.
The most nerving thing is the way how to edit the crontabs. There is unfortunately no simple interface delivered by default or I did not find it, yet. Normally, it is required to open a text editor and know the format to do changes.
The developers from abstracture did not sleep and created a wonderful application named CronniX which is a fantastic easy and simple interface to match exactly the task to edit the crontab.
CronniX