thanks for your query.
can be used for postponing periods, int he dosage directed by your gynecologist.
Theoretically, chances of conception a week before the periods is less, but ovulation is an unpredictable phenomenon and its timing may vary each cycle, so you should not take chances.
Also, using this rhythm method for contraception
is least reliable.
You should be using proper protection , and a reliable, constant one.
can be taken after unprotected sex, but it might interfere with your normal periods, and your purpose of postponing the periods.
It is also not recommended as a planned method of contraception.
You should use barrier method in this month before choosing a safe, reliable option next cycle onwards.