Okay, let me back up just a bit and talk about the install of the headliner (aka Step 2).
First is getting the old one out. Patience is the word here, little screw drivers, razors, and tiny needle nose helped me. Two words of caution:
1. Watch the bow ends carefully, they are spring loaded and if your attention is on one side of the aircraft the other side may be scribing not-so pretty patterns on the inside your windows (experienced that, fortunately it was on a back window and I think I can buff it out). Ditto when putting the bows back in. A second person is a blessing when handling these things.
Mark each bow so you know where they came from as they are different lengths. I used short pieces of blue painters tape, one for the first bow at the front, two for the second, etc.
2. Try your best not to damage any of the teeth that hold the headliner in. Enough will already be broken, no need to destroy any more.
Once the old headliner is out look at each and every tooth and align as necessary - VERY CAREFULLY so as not to snap them off. I used a very tiny pair of needle nose pliers. Take your time.
Also measure and mark the center (forward facing) of the roof supports the bows were attached to. This will be used to center the headliner.
Lay the new headliner out on a table, bow pockets up. You'll want to mark the center of each bow pocket, JUST THE BOW POCKET NOT THE HEADLINER MATERIAL ITSELF. Mark the side facing the front of the airplane. You'll align this with the centerline you marked on the roof supports. You mark the side facing towards the front of the airplane because you'll install the headliner from the back of the plane to the front.

On my plane the back bow was attached to the ceiling via little loop looking wires, forward of that each bow was held as you see in this picture.

As we moved forward with each bow we worked to keep the seams as straight as possible. Once we had all the bows in place we moved to the back of the plane again, adjusted seams as required, and used a blunted and rounded (on the ends) putty knife to push the headliner up into the teeth. We went from one side to the other, one section (between seams) at a time.
Once the headliner was in it was time to paint and install back vents and shoulder harness plates.

Back at it in the morning.