as you had intercourse at the end of your menstrual cycle in case of regular periods there is less possibility for ovulation during that period so the chance of pregnancy
is also less,
you can take unwanted 72 which is emergency pill within 72 hours after intercourse, which will help in preventing pregnancy,
if you are taking about unwanted kit
used for termination of pregnancy, you don't use it now, wait for one more week possibly by that time you can get your periods, if not consult gynecologist to get examined for the possibility of pregnancy then if needed with her advice you can take the tablets.