It depends from person to person. Some people get it after a week, some after one month and some won't get a breakout at all!
I had my initial breakout after 7 days and it took around two weeks. During the breakout i got around 15 whiteheads every day but they dried up the same day, just dont touch them! One month after starting accutane my face was totally clear from acne.
Goodluck with your cycle.
I just started this month but mine happened on around day 17 and lasted till day 23. (I am on day 28 and since day 24 I haven't gotten a single one) It is different for everyone though you might have one you might not. Stay positive throughout that time if you do get the IB it'll get better!!
This is my second time on accutane. Last time I was on it I had a pretty bad breakout at 5 months. Yup at five months. I actually have a log on here from my first time on accutane and I been comparing it to this second course. Im on day 21 today. I have had some new pinples but nothing I would call an initial breakout. I hope I dont get one this time.