If you're having a new home built or thinking about it in the future, you should know that precise preparation will result in a longer lasting home and a quicker construction time. I'm an expert in the field of New House Underfloor Connections and Excavations and know how the process should flow from step to step.
I would also recommend that any inexperienced owner consult with a knowledgeable earthmoving contractor to educate themselves on the basic steps right up until the footings are laid. Because once that slab of concrete is laid, it's a major exercise (and cost to you) to fix it.
This is a job I did recently at a new house site, excavating the trenches for the underfloor sewer and connection points to the front of the property. These need to be accurate in depth and in width as a minor increase to either can result in a lot more concrete being needed at a cost to you.