If you insist on any partners having the same BAEC renewal date, it decreases your pool of potential mates by a factor of one twelfth unless you can find a BA virgin who interests you and convince that person to go for it, perhaps by giving them a gift of an upgrade or whatever. Champagne might help.

Fortunately legacy USA carriers don't create this problem as the elite (re)qualification year is the calendar year for everyone unless you're doing some special status challenge.