Bassinet seats

Does anyone know when bassinet seats are released for long haul flights for seat selection? Most airlines I've flown on release them for open booking 72 hours before departure time, but I couldn't find any information on Cathay Pacific's timing.

My husband and I (no kids) prefer to reserve bulkhead seats for long haul flights, but usually the first and last seats in a 2x4x2 formation are blocked for bassinets.

Thanks!