How Long Does Cytotec Tablets Take To Completely Abort?

Hi I am 7 weeks pregnant today. Tuesday night I went to a doctor for a medical abortion and he inserted 4 Cytotec pills in my vagina. That same night I had slight cramping but nothing since then. Since then I have also expelled the tablets in a brown powdered form. However I am yet to see any bleeding occur. I am confused, is this supposed to happen? The doctor told me it may take a couple days, but how long? or does it mean it did not work?