One week on accutane, seeing no difference at all?

Hi, I am a 21 year old female and have just been prescribed accutane. Today marks day 7 of taking accutane. I am a little worried because I have seen no improvement in my acne at all whatsoever. Not only this, but my body doesn't seem to be reacting to it at all, I have no dryness, no chapped lips, nothing. My skin is as oily as ever and I guess my question is, when will I start to notice something happening? Has anyone else had something similar happen to them? Thanks!