Have the plumber install the rough-in plumbing. He will know, based on the concrete slab elevation, where the pipe will "need" to go through the wall, (maybe even under) Pipe grades down at 1/4" per foot, which will need to be considered.
Good Luck
Terry

: I am planning to build a basement, and have a septic system installed.

: For the rough-in plumbing, does the 4" drain line for the bathroom come through the concrete slab at the inside edge of the footer?
: (I had better hire a plumber for this, but I am still curious)