Use Year refers to the month when you receive your allotment of points. Using an April Use Year as an example: You receive your allotment on April 1, 2001. These points must be used by March 31, 2002. Your deadlines for banking and borrowing points play off of this "Use Year".
The only time Use Year really matters is when you have to cancel a reservation. Using April again....if you have a
DVC reservation for July 2001 and cancel before 30 days, you'll have no penalty and be able to use your points for any other type of reservation, and even be able to bank the points. If you cancel less than 30 days, out you'll be in "Holding Account" which means you can only use the points for reservations made 60 days ahead. Both still give you lots of options.
If you have an April Use Year and you have a reservation for March 15 and you find you have to cancel in February your options are now limited. You are past the banking deadlines. You cannot make non-DVC reservations once you are into the final 60 days of your Use Year. Your only real options are to let someone else use the points (or rent them) or to take some type of DVC vacation before March 31, 2002.
All in all Use Year isn't a big deal. If you know when you'll be vacationing (at least for the forseeable future) you might want to try and get a Use Year that would leave you flexibility around the time you like to stay should you have to cancel.
Use Year has no bearing on making reservations 11/7 months out.