My experiennce with GC's and new construction wiring;
GC mostly doing all wiring "in house" not looking for an electrician other than sometimes for the service set up, or when they get into a jam because "Not sure what happened, but can't figure out where this wire went".
GC that is hiring an electrician is looking for the "cheapest" and fastest. One man operation not generally getting hired for new wiring jobs for whole house residential.
GC not usually giving a timely notification that your service will be needed. Usually calls and want it start tomorrow, and done in just a couple of days because they scheduled the insulation company for later in the week. If you're not available at the drop of the hat, they don't bother calling again.
Tell the GC "IT" can't be done that way or, to meet code it must be this way; you won't get called again. GC's around me are kings of "Can't your Just".
BUT if you are intent on this work with multiple GC's,
Try googling for GC's in your area, finding out who the owner is and schedule a meeting with them to discuss what you can offer them and what they could use from an "electrician" rather than maybe already in house operation.
Maybe even scheduling a meeting at a job site with a GC & show up with a box of donuts and carton of coffee from a "Good" donut shop for the "Guys", with business cards in hand. Getting in good with the framers, if you get the jobs from the GC, goes a long way in making your life easier. Give trhem your card too as they also know people that might get you work too.