Something else to keep in mind now that you mention "The devil is in the details". Truer words were never spoken!
Here's the thing...
Assuming you are using PVC drain pipe and "slip fittings". Once you apply the adhesive (don't forget the primer) to the pipe and socket of the next fitting you are committed. You can not un-fry the egg at this point.
In assembling the pipe critters you only have about three seconds
to get your act together before the assembly seizes and there is no going back. You must have already mixed and placed the sandmix, and heaped it high enough to effectively receive the pan while at the same time not having too much mix so as to resist the proper positioning of the pan in what is to be its final resting place. You need to be able to apply the adhesive then lift and properly stab the drain onto the drain pipe then push the pan into the fresh mud at the same time. Loose mud is much better than tight mud in this case.
Once the pan is stabbed DO NOT get on the pan for any reason. If you do, this will likely compress the sandmix under the pan more than you want it compressed and if that happens you have defeated the purpose of having the cement there to begin with.
This is all very do-able but the devil is indeed in the details