Having tried to love cranked nipple drivers and failed, I use an offcut of spoke with a nipple screwed on the thread and superglued in place. The remaining length of spoke is then covered in gear outer cable in whichever colour one fancies (I favour a selection and make a choice on mood that day). The end neatly covered with a ferrule. And a lightweight B&D cordless screwdriver.
Once all the nipple have been screwed on a few turns, I lay the wheel horizontally on my lap, with the valve hole at 3 o'clock as I look down. Then with the B&D driver held horizontally in the right hand, it gets inserted into the first spoke by the valve hole, without the need to look*, it engages with the nipple and screws it down until it's at the end of the spoke thread - either by placing one's thumbnail in the last thread, or simply by eye. The wheel is turned and all is repeated until back at the beginning.
*not so easy when using single eyelet rims or deep section horrid carbon fibre b*sta*d rimsThis method does benefit from using reasonably accurate spoke lengths, but by no means ultra critical. There's enough torque in the driver to drive the last few spokes down, if the lengths are about right - and bish bash bosh, there's already a bit of tension in the wheel and it's even enough to bung in the jig and get started with the spoke key.
If the spokes are too short, one has to back them off a tad with the B&D until a few threads are visible and all are roughly even by eye.
If the spokes are too long and still loose after the nipples have been driven to the ends of the threads, it just takes a couple of goes around the wheel in the jig with a spoke key until there's enough tension to get into serious mode. One gets a feel for how loose and how many turns each nipple needs to take up the slack. Sometimes it will be two whole turns and in extreme case it can be up to four turns of the spoke key.
When I calculate spoke lengths myself, I'm fairly confident driving the nipple to the end of the spoke thread is going to be in the right ball park. When I used to build wheels for my LBS and just used to cycle over as and when wheels were needed - the proprietor usually had all the components laid out ready, or at least a list based on his calculations. There were many times when this was a bad thing
I much preferred or was more confident in the spoke calculater I used than his