If you don't know how much time will spend and when you will urbanize and build, this is the method you have to use. You only have to intro the value of four parameters:
1.- ¿How much can you get of saling the building product? That's the PRICE OF BUILDING.
2.- ¿How much urbanize the land will cost to get really urban land? That's the COST OF URBANIZING.
3.- ¿How much building on the land
will cost? That's the BUILDING COST.
4.- ¿How much can you construct on the urban land according to laws? That's the FLOOR AREA RATIO.
Try tu put the values and click on "Calculate". Change the values and try again.