john.straffin, the first time that a repeating task is completed, it will automatically set the due date for the next occurrence (so if a task repeats 'every week' and is completed today, the next due date will be a week from now).

If the task hasn't been completed yet, you'll need to set the initial due date that you'd like the task to repeat from. Hope this helps -- if this doesn't answer your question, please let me know. Thanks!