I always tell my birthing mamas to do a test run with their pools around 37 weeks or before. No need to fill with water, but definitely inflate it and make sure it holds air over night. Here's a quick video showing just how easy it is to set up your birth pool!
Also, it's really crucial to fit the sink adapter and hose to the your water source ahead of time. Many a laborer hasn't been able to figure it all out in the moment, and that stinks to not have the tool you want in your labor.