While you can buy BCV through Disney, you are going to pay between $30 to $40 per point more. I believe that BCV is still going for $115/pt from Disney when the resale market is running between $80 and $85 for that resort.
If you travel in March, then having a Feb or March UY would be ideal since you want to have a UY that starts just before your typical travel to allow for the most flexibility if you had to change or cancel a trip. By having a UY just prior to travel, if you did have to cancel or change (at least 31 days out), then you would have a lot of time to rebook the trip or bank your points.
Since you would be going resale, Dec UY would also work. Besides March, is there another time of year that you might travel? Sometimes, looking at that can also help you use a UY. No one UY will work for all travel times, but it can help if someone does have some typical travel patterns.
I teach so our times of travel are the summer right now. In addition to that, when I retire, we plan on traveling in the Fall and early winter so we went with a June UY because it worked for both.
Good luck!