The average menstrual cycle lasts about 28 days, but it can vary from person to person. If you started your period on November 9th and have a typical cycle, you would likely expect to start your next period around December 7th.
If your cycle length is different (for example, 30 days), you would adjust accordingly (in this case, you would expect your next period around December 8th). Please keep in mind that individual cycles can vary in length and regularity.