You need to get the animal out asap but not expose it to salinity or temperature shock. We receive a fair number of shipments and I try to anticipate problems that I can solve. First, I have received octopus from 28 to 36 ppt. Acclimation can take awhile if the shipping water is very different from your tank. You can ask the shipper what salinity will be used, but that is not always what you will receive. We keep a supply of hyper-saline water (36 ppt). We also have access to DI water. When an animal arrives, in literally seconds we can measure the salinity in the bag using a refractometer and if necessary, calculate how much DI to add to the hypersaline water to achieve the correct salinity.
Temperature is more difficult to deal with quickly and in a case of inking, changing water should be the first priority. However, I do have a supply of sea water in our cold aquarium room (15 C) and if necessary, I can mix cold seawater with that at room temperature to quickly match 33 ppt at the desired temperature.
This is probably overkill for the average home aquarists, but it probably has saved a few animals that we have received.