Step N.b (Main second floor staircase) As I am going to use the under-stairs closet for my toilet, I fitted a cardboard cover underneath the staircase and covered it with wallpaper to match the wallpaper I already used on the two walls. One tip: check the fit of the tabs at the bottom of the stringers, into the slots waiting in the house, before assembling the staircase. I didn't do this, and my tabs were too long, so I spent a difficult time wedging the extremely tight fitting staircase in and out of the gap trying to trim the tabs short enough to get them into the holes. Also, I did not assemble the Upper Section ahead of time, I waited until after the main staircase was fitted before gluing in the upper stringers. I found that I needed to trim the Upper Stair and Upper Riser shorter to get them to fit in the gap.
Step N.c (Attic Railing): the instructions say that Attic Railing 3 is already in place, but it isn't. I glued in the front railing 2 first and I wished I hadn't later, because I found that it was too wide and pushed the end of Attic Railing 3 too far to the right. If I were doing it again, I would glue in the long side railing first, then trim the front railing to fit.
Step N.d. (Stair back, install staircase): although the instructions say to glue in the Second Floor Stair/Back first, and then slide in the staircase, I found this impossible. The stair was too tight a fit and I couldn't see where the (non-fitting) tabs were. In the end, I pulled off the back (luckily the glue hadn't completely set) and installed the staircase first with glue only on the lower tabs. Then I put the back in again, and pushed the staircase down to the correct final position.
After that I glued in the upper stringers, riser and stair. A little bit of wall substitutes for a riser between the main staircase and the upper staircase - I covered this up with a bit of stained wood to blend in with the staircase. The last step was to glue on the handrail.
I wish I had known ahead of time that the outer edges of the floors, and of the two second floor walls, were all going to be on display. Mine had become corrupted with light-coloured paint, and yet really I want them to be stained to match my stained stair back and stained floor edge trim. I think I am going to have to do some camoflaging with brown paint. [Postscript: later on, I stained a bunch of coffee stirrers to match, and glued them over the exposed tabs of the bannisters and around the Stair Back which makes them look much neater. I also stained some chair rail moulding, and applied it like skirting around the outside of the bannisters, and along the base of the bannisters to hide the seam with the wallpaper.]
Step N.d.6 (Upper Section Stair Back): I found that I got a better fit by bevelling the top and bottom edges with my Dremel tool. This will be painted the room colour.
My understairs bathroom closet.
While waiting for things to dry, I have been working on some of the cosmetic issues, like filling in unused slots, and covering up tabs on corners with the right angled moulding I bought.
Step O (Porch Assembly): As I am installing a set of French doors to be my shop entrance, I trimmed away the centre post on layers 1 & 3, and only left some gingerbread on layer 2 to support my door. This was fairly straightforward to assemble - I laminated my layers by weighing them down with soup tins rather than the suggested masking tape. I think the hard part is going to be achieving a smooth finish on all these plywood edges.
Step P (Balcony Assembly): Again, straightforward, although curiously the instructions don't actually tell you to glue in the central bracket, but you can clearly see it in the photograph in the instructions so I glued it in after taking this photo.
Today I spent a few hours punching out everything else on all the sheets, grouping it (small window, kitchen bay, etc.) and putting each group in a labelled zip-lock bag, and checking the instructions to make sure I have found everything. The only pieces that seem to be missing are some foundation trim for the front of the porch, and I can make that from some of the leftover scraps. I am basically down to all the trim now (apart from the roof which is still waiting for my lights). Suddenly I feel like I have reached the summit and am starting down the other side - I have a house now... it just needs an awful lot of trim. And all the trim has to be smoothed and painted first.