38 terabytes = 304 terabits.
304 terabits / 1 gigabit/second = 304,000 seconds
304,000 seconds =~ 84 hours. Add 20% for not pegging the line the whole time and the limits of 1gbps ethernet, and perhaps 100 hours is reasonable.
whatever the download size is, you're bottlenecked by the remote server's up speed
