Depending on full time or part time studies. Full time, you need around 5 months. Part time study, you need at least 7-8 months. Accounting has very little to do with FRM. CFA shares around 25-40% common knowledge with FRM. In conclusion, if you can manage to read the FRM handbook five times and do all actual FRM exams since 2000 (including FRM practice exams) five times, you should be fine. Schweser notes are helpful for understanding the handbook but do not rely on it.
Depending on your situation described in your question, if you want to pass the full exam in Novermber, I think now you should begin to prepare because FRM is greatly different with accounting. FRM includes a lot of statistical and mathematical models. In addition FRM has a great number of complicated points to remember.