I think it varies for everyone.
My experience: I have moderate facial acne, severe body acne. Was on birth control pills until no longer effective, had reaction to tetracycline. First two weeks on Accutane, face cleared and looked great. Third week, significant drying but face still looked good although makeup started looking a little pasty. This week I've started breaking out but my face looks different everyday. Some days my face is more red/splotchy, some days I'm more dry/peeling, some days it looks like it's healing. It can even look different at different times of the day. I'm hoping this part passes soon and I go back to being nearly clear =) I have seen a slight improvement in the body acne.
Good luck to you!
Thank you! And I hope everything gets better for you too! Acne isn't an easy thing and I hope you get clear quick! My goal is to be 100% clear by summer. =)