Go get a few bottles of rubbing alcohol and a spray bottle now. Remove the white fluff with an alcohol soaked cloth or brush, then spray the whole plant, including the dirt. Sometimes they like to hide at the base of the plant just under the dirt. I just discovered a colony of mealybugs (30+!!!) on one of my echeverias and I am still amazed I didn't notice them sooner. They are VERY good at hiding in the nooks and crannies.

A cotton swab dipped in alcohol works well to remove mealies. Remove what you can see, spray the plant (I used a 50/50 solution of the alcohol and water, but full strength won't hurt), and repeat in about 5 days. Keep an eye out for more showing up and hop on them immediately, as April suggests. They will spread to other plants, so keep an eye out for them on all your plants.

Eugh, thought so. No idea where they could have come from as the Jade has been indoors & I haven't brought in any new plants over winter... Ah well, it's in quarantine now until I can get to the shops!