When I was on Apri Oral (21-day active and 7-day inactive pills), I never got my period until the 5th day of the inactive pills (a thursday since I was a sunday starter). I just recently switched to Yaz (24-day active ad 4-day inactive pills) and my period didn't show until the very last day of the inactive pills (and at 7 p.m. at night, at that!)

It's common not to start your period right away when you go on the inactive pills. The bleeding you get from your inactive pills is hormon withdrawal bleeding, and it will take a few days for the hormones to withdraw from your system.