I like to check everything when I am finished to make sure it fits & works properly. Take the roof off & check your work do all the 2” x 4”s line up, are they straight, is the trim work around the doors to your satisfaction, do all the doors open & close freely & smoothly, are the roof trusses straight, is the paint to your liking, etc.
Now set the roof back on your diorama building does it slide on smoothly with no binding or forcing, do the roof trusses fit nicely, are the end of the trusses straight & even. Is your building square, is the concrete foundation even all the way around the building.
If there is anything that does not work properly you may want to correct it now because you may decide that you want to build a full scale diorama around this building or use it as an out building & make another style building to go with it.
You could build a house in this similar style & era that would go with this building & build a full scale diorama now that you have a few of the basics to making this starter building.
I will keep getting into more advanced techniques as we go along & build different style buildings, these buildings will be in a full diorama scene with the accessories, vehicles, figures, etc.