A different option...Ask your LFS what there SG is and if you are not using a QT then slowly make your tank match theirs within .001, if using a QT it will be easier and you don't have to mess with your tank parameters, even if you can set up a bucket for the shrimp with an air stone and a heater it would help.
Then make the bucket the same SG as the LFS, float bag 15 min closed to match temperature, check the SG just to make sure it is the same as you made it in the bucket, then simply put them in the bucket. Then over a period of a few days make the bucket water match your tanks SG, when it matches and they are fine and temps are the same just put them in the tank.
This is a successful method for when things are shipped because ammonia builds up in the bag and becomes toxic when the bag is opened-->increase O2-->increase pH-->ammonia becomes more toxic.
When I got my fire red cleaner I didn't know this method, instead I drip acclimated him for 3 hours because my water was so far off from LFS. He did fine. I did this other method with all my fish, corals, snails and shrimp to move them to a holding tank and everyone did fine. It was a lot less stressful on them (and me)then if I had drop acclimated everyone.