A block building is typically laid out in increments of 8 inches both horizontally and vertically to minimize the labor of cutting block. Thus your block rough openings would be in some increment of 8 inches, say for example 4'-0" x 3'-4". The location of the block rough openings top, bottom and sides would be some 8 inch increment measured from the end of the building and from the bottom of the first block laid on the foundation. (Draw yourself a sketch) As for as details for framing the windows it will depend on the type of windows you are using, metal, wood, etc. Who ever you are getting windows from should be able to provide some details. Your mason should be able to guide through the details and work with you are on the window sizes. Just need to track down what you are thinking about for windows first
