+1 for drip acclimation, how long depends on how different the salinity is from source water to your tank water.
For example, I got an urchin recently who came in 1.030sg (!!!) salinity, so I took an hour or two to slowly lower the acclimation vessel down to he 1.025sg in my tank. Once the salinity was even, I floated the vessel to temperature acclimate. Honestly, we should probably be using this kind of care for most snails, shrimps, and other critters.