The installation must be done correctly the first time, while you were building your house. It is critical to have everything in place, so you are not ripping off drywall later on if something was missed.
Before building any wall, the constructor always works with an electrician to make sure they are on the same page for how they will install all the outlets, switches, etc.
The plan of the house must be seen by an electrician simply because it is better if he tells you there are some problems with the electrical process before starting building than after, just imagine, it would be a catastrophe if you called the electrician later after finishing half the construction, and the cables and wires cannot be fixed. In other words, the electrical in new construction is fundamental.