understanding clomid

I'll be starting clomid next month and noticed some women here are taking it on different days. Why? What does clomid do when it's taken on different days? From my understanding is that my egg isn't developing as well as they like and by taking clomid on days 3-7, they hope it'll be more develop for when it is time for fertilization. My problem is a short luteal phase (9 days), my ovulation is also later than they would like (day 16), and my period comes to early given my other factors (26 days).