There's no rush, especially when building a diorama. It's taken me one and a half months and 120 hours on the Halifax alone for my diorama, and I haven't finished it yet, and still have to start on the base and figures etc.
The trick to getting a good result in a diorama, is careful planning beforehand, and knowing what every 'person' (figure) and vehicle are supposed to be doing in the scene being depicted. Each piece should sit in the diorama, not on it, and be posed in such a way that it's obvious to the viewer what is happening, rather than having a figure just standing there, stiff as a tailor's dummy. Also, each piece should literally fit in, in as much as items like oil drums, packing cases and so on, should look as if they're on the ground properly, and not sitting above, for example, the grass.
Looking forward to your progress, and don't be afraid to ask if you need help, advice, or suggestions.