Walaikum Assalam. FA2 usually takes a month to refresh your learning. If you’re referring to starting from zero and studying the content in a month, then i would say it takes more than 1 month. The syllabus is bigger than FA1 and some topics such as Depreciation, Bad Debts, Suspense Account, etc are new and difficult for some students.
But, it all depends on student’s own determination and commitment. Some have done it in much lesser time while some have taken more time. In the end, its your time management that determines how much it should take.