Once the bottle's capped and before the sediment has all settled out, there's no harm in shaking it around some - any oxygen in there is going to get in the beer either way, and any settling is going to have to happen anyway. It's just that if you've done it right the headspace doesn't have enough oxygen to really damage your beer. Even after bottles are conditioned and the sediment falls out, it seems like if settles a lot quicker after shaking than it took in the first place. If you're really worried, I suggest oxygen-absorbing caps, then giving the beer a shake around after bottling becomes a necessary step instead.
I try to label as soon as possible after bottling, though. Not for the sake of the beer, for the sake of making sure I never bottle a new beer with an old one still sitting about unlabeled.