I've got it down to about 4 hours on brew day, but I do most of the prep work the day before. I'll mill the grains, prepare my water, and get all my equipment out the night before brewing. Then I set up an electric bucket heater in my HLT and put it on a timer so the water is at, or close to, strike temp when I wake up in the morning. I'm guessing that if I skipped the day before prep, my brew day would be closer to 5 hours.
And batch sparging is your friend...