Personally, I wouldn't drip acclimate or put the fish right in the tank if the salinity was low. You should be using a QT tank anyway, so when the fish arrives, add freshwater to the QT until it matches the salinity of the shipping water. After a quick temp acclimate, you can dump the fish right in. Over the next few days, slowly bump up the salinity in QT to 35 ppt (or whichever salinity you choose). If the salinity is very, very low, maybe do it a bit quicker. But salinity changes are pretty hard on fish. Take it slow.
If you can't adjust your QT's salinity because there are already animals in it (or you are not using a QT tank), set up a 5 gallon bucket with a heater and water movement (airstone, HOB filter, etc). Lower the salinity in the bucket to match the salinity of the bag, add the fish, then raise the salinity in the bucket over the next few days. Then, add the fish to QT or to the DT.
My last fish (from Unique Corals) came in 35ppt water, so I didn't need to do any adjustment. Had I needed to, though, I would have done the bucket method. I already had corals in QT and couldn't drop the salinity. Thankfully, the salinity was perfect. After a quick temp acclimation, the fish went right in.