The interplay:
1. What use year month you have has nothing to do with when you can go (any time of year) or when you can call to reserve (always up to 11 months out at home resort and 7 months out at others).
2. Where it might have an impact has to do with time of year you may go and the interplay between the issue of banking points and possibly having to cancel a trip.
3. The banking rule is that you can bank any or all of your points from one use year into the next use year at any time during the first 8 months of your use year but you cannot bank any thereafter.
4. Now assume a February use year. You get points annually on Feb 1. They must be used for a trip between Feb 1 and Jan 31 of the next calendar year, unless they are banked. You have until September 30 to bank your points into the next use year. After Sep 30, you cannot bank and any points left at that time must be used for a trip that ends no later than Jan 31.
5. Now assume you are a member who usually goes about the same time of year and that time is April. Back in May 2007 (11 months out) you reserved an April 2008 trip using points to be issued Feb 08. Mid-Feb 08 something happens and you have to cancel. Those points go back into your account and you still have until the end of Sep 08 to bank them.
6. Now assume your usual time of year going is Christmas time. Today you call and reserve Dec 08 using points issued Feb 08. End of Oct 08, something happens and you have to cancel. Points go back into your account but they can no longer be banked because you are beyond the banking window. They must be used for a trip that ends by Jan 31, 2009 or they will be lost.
7. Thus, if you have a usual time of year to go, you might want to consider getting a use year month that assures you can bank if you have to cancel. For example, if you go Christmas time every year, then a use year that starts any time from June to December easily assures that you will be able to bank if you have to cancel. Note, all this is essentially pointless if you tend to go at various times of year. Also, your regular time of going may change as years progress so it is not a permanent hedge.