So I've got a question ttc#3 first time using clomid

(Rebecca) • Im 33wife married 14 years and have 3 boys 14,9,3
So im suppose to start my clomid tomarrow im super excited!! Im suppose to take it days 5-9 but af seems like its ending today and I thought your suppose to take it ur last day but it seems to be ending a day early does it matter should I still take it tomarrow?