Actually, between April and Aug, Aug may be bettter for you under the current 4 month banking rule.
With an Aug UY, you need to cancel and bank by April 2. You also have to cancel more than 30 days prior to a scheduled vacation to avoid having your points go into the holding account. Holding points cannot be banked. So you would be able to cancel a Feb, Apr or Aug vacation more than 30 days in advance and still bank those points.
With an Apr UY, you need to bank by December 2. So if you cancel your February vacation in January, you could not bank those points and would still have to use them by March 31.
Best of luck -- Suzanne