I did some calculations of rear wheel force on each gear and plotted them in excel a while back from my dyno curve. I found on my car it's best to shift at redline in all gears, except about 100rpm before on the 4-5th shift.
First gear in my LX (auto n/a) is shifted at a hair over 5k and the rest about like Cro mentioned about 4800. I don't know why but my car pulls really good at 5000-5500rpms in first gear :scratch