I agree with Ken, wholeheartedly. Don't water until you have a few true leaves, and even then, do so sparingly. A lot of rooting hormone has some sort of fungicide, but that won't help much against rot caused by overwatering. As Ken said, you can mist them when warm or in sunshine, but in general, no water until leaves are formed. Plumeria are trees, and just like most trees, the roots mimic the canopy--bigger canopy = bigger root system. The first set of leaves opening up will let you know when you can start slowly watering.
