Preferably...you would want the shimp to rot and produce a lot of ammonia so that the tank bacteria would multiple on the
LR that you have. This takes time....weeks maybe...You would know if you were done if you can't measure any ammonia or nitrite in the system.
Until that happens, your tank can't support life.
As it is, I'm concerned that your new
lr.com rock is arriving too quickly. Your tank may be in the worst part of it's cycle just when the rock arrives. That's not good conditions to introduce your rock into. It's not all that bad, just not optimal.
I think you're committed at this point. Remove the shrimp a day or two before the rock arrives and continue the cycle using any death on your new
LR (as Phases suggests)
Got your test kits?..or ask your
LFS to test for ammonia and nitrite to tell you when the tank has stabilized.