I suspect what I'll do (though reserve my right to change my mind
) is start off with one character and play the game all the way through. I'll then use the info I gather on that playthrough to fine-tune my character concepts for other playthroughs. I'll probably then create a few of them that I think are most promising and perhaps run them through the prologue and see which one grabs me most for my next playthrough.
I might jump around characters and have them progressing in parallel after my first run, but I'd not try to do that systematically by taking them all to end of act 1 and so on. I'd just play one character for as long as that was what I most wanted to do, then skip to another if I were in a different mood one day. I find that the trouble with replaying the same bit with lots of different characters is that it can start feeling like a chore as I see similar content again and again in quick succession.
I haven't decided on my character for my first playthrough yet, though. I want to pick one who I think would naturally talk to everyone and explore everywhere, so I can see as much of the game as possible without sacrificing roleplay, but beyond that I'm still dithering!
