So the way we are doing it that will be the easiest for us is as follows. Run string lines for the exact size of the building. Squared up. Layout posts and drilled holes. Then set forms. Get posts in place screwed to form and braced to maintain level and plumb. Then pour posts and slab at the same time so all concrete is one pour. This is going to be a two person install and I really gotta do it the easiest way possible.