Andy,

It is better to wait until spring. When a plumeria is transplanted it will shock and stress even if the root ball is not disturbed. It is best to transplant when the plant begins its longest growth period. That is spring, now they are experiencing shorter days cooler night temps which will radically reduce natural growth. In addition, the plant will be be in an environment with excess soil that will not dry out. This condition becomes conducive to soil pathogens that can promote root rot. If you have a green house with heat and lights that can imitate longer days and warm nights it's not a problem.

Jack