It matters in terms of the flexibility if you ever want to change a trip or have to cancel.
For example, I teach and can only travel certain times of the year. We mostly go in August. When I first bought, I had an Oct UY. If I ever had to cancel that August trip after May 31st (the banking deadline for this UY), I would only have until September 30th to use the points. Since I can never go to WDW in September due to my job, those points would be lost.
Now, I own a June UY (sold the Oct UY contract). By traveling in the beginning of the UY and well before my banking deadline, I have a lot of flexibility in what to do with points should I need or want to change things.
If I canceled that same August trip, I would have until May 31st, to use up the points, giving me plenty of time that works in my schedule.
By choosing a UY that falls before your typical travel, it just gives you some peace of mind if something happens. Even if you want to downgrade your room size, if you are in the beginning of the UY instead of the end, you don't have to worry about the points.
I have friends that bought last year and went with a March UY for their Feb vacations (school teachers as well so they travel on our Winter break), because that was the UY being pushed by
DVC at the time. I tried to explain it to them but they didn't seem to care too much.
If something ever happens and they have to cancel that trip, all those points will be lost.
If you never cancel or trip or ever want to change a trip, then UY will be of less importance, but emergencies do happen. If you have a choice when buying, there is no harm, IMO, of getting a UY that will give you the most flexibility.
