My car 5s has about 270k on it so I don't like to "mob" or floor it so much, shifting out of first around 5200 (just a hair before peak power) and second at around 4800, and third around 4500. I clocked 8.4s and the calculator says I should do it in about 8.2. So not THAT OFF, I'm sure I could have gotten it down to 7 or so if I was rough with her.
Anything under 10 seconds is brisk enough, to be quick these days you have to be in the 5's and to even be considered fast you'll have to be into the 3's. In the last year or so I've come to the conclusion there's no point in caring anymore seeing as I can't afford something that's into the 3's and even then that's the threshold of what I'd consider exhilarating acceleration. 0-60 is pretty much useless in the real world anyway, the only time you'll do it is pulling out onto a major highway from a dead stop. Passing speed times and rolling start times are more useful and give a better idea of a car's capabilities in day to day driving.
Do you know that you can download an Accelerometer app on your phone and get direct measurements in ft/s^2 ? This is really the best way to measure how quick you are. You just need to strap it down to the dashboard someway.