Is it ok to take plan b pills two times a month . first time without period and second time on the day period starts ?. thanks

Check instructions: Plan B One-Step® is a single pill you take by mouth. It must be taken within 72 hours after unprotected sex or birth control failure. The sooner you take it, the better it works. Plan B One-Step® should not be taken as regular birth control. Plan B One-Step® is not as effective as using a regular birth control method correctly and consistently. If you have unprotected sex after taking Plan B One-Step®, it will not prevent you from getting pregnant.