Proper Houston swimming pool construction and excavation is tremendously important. The hole in the ground is the cast for your foundation -- everything else in the construction process follows your dig. If the pool is over, or under-, excavated, it will not meet the design requirements. A larger hole will not meet your requirements for your patio and landscaping. Sometimes, it will enter your easement. If the pool is under excavated, you'll end up with a smaller pool than expected. When the pool is excavated according to plan specifications, the rest of the construction should follow smoothly.
Don't forget, all of the dirt that comes out of the ground has to go somewhere. By the time the excavation is completed, that backhoe or bobcat will have filled up more than a few dump-truck loads. Maybe you figure you want to keep some of that dirt -- perhaps for a little landscaping when the pool is all done. I say some, because I don't think you're going to want all of it (especially gumbo clay soil).
Steel rebar is one phase of construction that should only be done by a pool specialist. The "grid" of rebar that the steel workers will lay is both the reinforcement for the gunite to come, as well as the basis for the actual shape of the swimming pool. After the excavation, the curves of the steel rebar will dictate the curves of the pool. The basic shapes of the steps and benches are determined at this point. The rebar is the foundation for the gunite work to come.
Along with the electrical, electrical grounding and plumbing, the steel work is a phase of construction that needs to be examined by building inspectors before the gunite is applied. The steel is engineered to the specifications of the swimming pool builder and structural engineer employed by the swimming pool builder. The steel rebar phase of the construction of your swimming pool is usually completed in one day.