A bit of clarification. You can bank points only from one use year to the next. The act of banking must be done by the end of the eighth month of your use year from which you are trying to bank points (e.g. if you have a Feb use year, banking must be done by end of Sep the same year). As long as you follow that rule, you can bank multiple times, e.g., some points at 4 months into use year, more at 5 months, and then the rest at 7 months.
Once banked the points must be used for a trip that ends no later than the end of the use year into which the points have been banked, or they will be lost.