Yes, if you think you might have to cancel a July, August or September trip after May 31, an October use year means you cannot bank the points and have to use them before the end of September (or they are forfeited).
A June trip isn't a problem as long as you cancel at least 31 days in advance. If you cancel on time, you'll still have time to bank. If you cancel any trip 30 days or less before arrival, the points go into holding status and in addition to booking restrictions, holding points expire at the end of the use year.
For anyone who may not know, use year has nothing to do with when you may call to make a reservation. No matter what use year you have, you can always call 11 months prior to check out for a home resort and 7 months prior to check out for a non home resort.
In general (if you have a choice), it's best to get a use year that is no more than 6 or 7 months prior to the time you usually travel. Keep in mind that over the course of your membership, your travel patterns may change. A use year that starts out "perfect" may not be so perfect later.