Instant Effect
On Star Trek, Doctor “Bones” McCoy will administer a cure and it will take effect immediately. We see the same things on the other incarnations of Star Trek, and in other TV shows. It’s pretty dramatic to see a cure work immediately, but cures tend to take a few minutes at least, if not hours, days and months. Even if the disease or whatever is killed instantly, the damage and growths still take time to repair. Do your cuts heal in seconds? No, so neither would a blister or growth.
On a related note, we never see victims of disease/damage/etc. who are instantly cured get -any- side effects whatsoever. Even when the treatments/conditions/whatever. were never before encountered.
However, it should be noted that perhaps, in the future, medicine will take on true ‘reconstructive’ procedures, i.e. being able to ‘build’ living organic tissue, rather than coaxing/aiding the body’s own repair mechanisms. Although I doubt they’ll be so dramatic and sparkly as Star Trek’s insta-cure™ tech, but perhaps it could work at similar speeds. Then again, even that would have its own limits and implications.