ITC can be claim in full in one Go on same month in GSTR 3b
if you are supplying both taxable & Exempted supply the ITC attributes to Exempted supply has to be reverse every month in 3b for 60 months. Refer rule 43 of CGST Act
the reverse condition is only applicable when you are dealing with both taxable and excempted goods..... if you are dealing with both type of goods then u have to reverse ITC Month by month i.e in 60 months