You want to make schedule, you need to set up properly. This means the GC is going to have to alter his 'routine' a bit, even do some 'temporary' stuff that he'll need to take apart later. Hold his feet to the fire; these 'extras' will let everyone work faster.
#1 is to have power on site and a toilet. You can't afford the time it takes to drive to a gas station when nature calls.
Having a real, functioning toilet is a priority, even if that means a cheap toilet hooked up in an unfinished bathroom. Along the same lines, trash has to be MANAGED. That means a well-placed dumpster, not random piles that you're always moving about. Most jobs could use a guy just for housekeeping.
Close behind is the need to close the place in, get it out of the weather. Cover the windows and doors. String some temp lighting. Set up heaters. Forget the 'tough guy' crap; everyone works better without jackets and cold hands.
Access is critical. This means being able to drive INTO the garage and having at least temporary stairs. You lose time when you have to climb or fuss with ladders. This means the GC might have to do some temporary grading. There's nothing like slogging through soft mud all day to slow things down.
Site security counts; you need to be able to lock the place up, even if the lock is a hasp and a sheet of plywood, rather than a real door. You don't want to come in and find yesterday's wire missing. Along these lines, MANAGE material deliveries and storage. No one is helped when you spend three months stumbling over stacks of drywall in every room.
Finally, set up a serious work station, where you can sort and store your parts and tools. Some stuff you'll have to order, so you'll need a place to store it until you need it. This might mean renting a trailer - so make sure there's a good path between the trailer and the house.
Don't expect any of this to be an 'easy sell.' I had a job similar to yours, where the GC scoffed .... until he came to check on me as I worked in the lower level. I had closed off the section, had a heater going, and was cranking out work with a cheerful helper. Upstairs, everyone was slogging through their tasks, slow and unhappy and wrapped up like the Michelin man. Seeing the difference first hand, the GC made some changes upstairs; suddenly it was worth it to board up the two openings where the 'special order' windows had not yet arrived.
For your part, plan on having 3 men and two vehicles on the job. Two guys to work, one to 'support' and make parts runs. One of the vehicles can even be a small car - it can carry everything but pipe. Make sure your guys have cell phones and can communicate. The "runner" can also be quite useful in documenting the job. Lots of notes, sketches, and pictures of everything!