6. Placement of basic resources, then the rest exists. You have 3 levels of buildings. I was rather thinking about something like in Settlers (or their remakes like Widelands): you place a building, then it is built and it takes a while. Then it can produce.
I know that this is very code-expensive part, but it is very pretty and from human position there is a progress of building up everything.
Of course it is only my opinion and it is not mandatory. Your game is good already :).