Builder/Developers are CROOKS
Is this your property and they are your contractor? Or are they builder/developer and you have a preconstruction signed contract for a house in their developement?
In my case the builder required me to obtain a "construction to permanent" loan thereby selling me the property up front and they became my contractor. Since they did that (a mistake I made them pay for dearly) I was able to control the job site and the construction loan draws (purse strings). You take away the right for the contractor to take their draws without your approval and watch how fast they answer your phone calls.
I went in after the stud walls were erected and after the electricians roped the house to install my stuff. As long as what you do meets the code and you arrange to have your work done prior to electrical inspection, you should be all right.
If it's not the case, try to be there when the electrical contractor is roping the house and slip him a few bills. You'll be amazed how cheap you can get work done that way
I would stop by once in a while when the different subcontractors were on-site, inspect there work, give them "something cold to drink", slip them a few bills and get anything extra done I wanted. The builder was none the wiser and they ended up paying for it.
Once drywall goes up it's too late. It will cost 4 to 5 times as much to do the work. Not to mention the thrill of climbing in the attic