NuvaRing

Okay, i have been on the pill for four years now and i decided to switch to the ring. My doctor advised me that nothing should change with my period. But last friday is when i took the ring out for my "period week" its monday and i still havent started or have had any sign of starting. When i took the pill i would start on sunday and end on wednesday. Just wondering if anyone that has taken the NuvaRing has experienced the same thing, or if i should go get a test.