For coral fragments, I basically do a combo dip/acclimation. I start off with a quarter cup of bag water and about 10-15% iodine. If there are any pests, they'll start doing their little dance within the first few minutes, and I bring the iodine percentage to 25%.
If there are no pests, I'll add a quarter cup of my tank water every 5 minutes, until it's a full cup. Than in it goes.
If there are pests, than I just let it sit for several hours until I'm certain they are all dead. Than I'll add my tank water at the same rate above. You just never know, even when your familiar with the other person tank, so I always examine the frag carefully.