I'm in Australia, so it's mid-winter here.
I'm very keen to prevent my hives from swarming next Spring/Summer (Oct-Dec).
I'm trying to stick to requeening every 2 years to minimise this.
Of these hives, one was a mid December 2014 cast swarm, the other was requeened in late February 2015.
They'll turn 2 in Dec 2016 and Feb 2017 respectively - when should I requeen, when they turn 2 years old (Dec 2016 and Feb 2017) or at the start of their second full summer season (ie this springtime, Oct-Dec) or in Spring 2017?