All I did for vector was draw the banks of the main river (a second river, not shown in this inset view), the coast, the bridges and the street plan. I did not create any vector buildings. Once I traced the different areas, cut canals, the banks and shores, I traced the streets. Then I started to hand-draw each building individually looking at the street plans. Deciding as I go along where a temple should go, a cemetery or other fiddly details. But I almost never do pencil only, as it would need to be inked afterwards - and I hate drawing things twice. So I always draw with pen from the get-go. The vector was just to aid me in overall layout - not individual building placement.