You can write your own formula for TS_ORDER if you want features to appear in an order not provided by the TimeScope Wizard. Remember that buildings are built in order from lowest to highest value of TS_ORDER, and that the results must be numeric. For example, to build features on the basis of their proximity to a road OR a town, the formula for TS_ORDER would be
Min ( MinDistance ( [ Layer:Roads ] ), MinDistance ( [ Layer:Urban_Center ] ) )
For more information, see Specifying a TimeScope build order.