Our solar systems position when the Sun's volume engulfs earth?

I am writing a novel in which the time is set to when the sun, after becoming a red giant, has reached earth. In my tale, humanity has kept the earth shielded from destruction however will instantaneously release all shielding. I start the chapters with a position in space, i have our current position, but not in the rough 5 billion years from now. Any help would be greatly appreciated, thank you.