It takes about 4 days and everything is done in 12 hour increments. You don't have to be precise about the 12 hours - just think twice a day - morning and night. Hands-on time is minimal. Note: Different seeds take different amounts of time. The seeds I use are tiny and are ready pretty fast.
There are all sorts of fancy contraptions for sprouting. I just use a mason jar with a bit of screen on top.
The first step is to put in a scoop (a heaping Tablespoon) of seeds and some water (an inch or two over the seeds). Let it soak for about 12 hours. The jar doesn't need to be in direct sunlight. Indirect is fine. I've also had no trouble in fairly low light areas.
From here on the jar will be upside down. Pour out the soaking water. Rinse the seeds. Prop the jar upside down and leave it for another 12 hours. I use a book display stand to prop my jar. It works perfectly.
After the first 12 hours of draining, you'll probably see the first signs of sprouting. Please excuse my blurry photo.
Every 12 hours from here on do the same - rinse and prop upside down to drain. Each time you rinse, you'll notice the sprouts are taking up more and more room in the jar. You'll see more and more green.
After a few days of sprouting, they are ready to use. I love adding them to soups, sandwiches, and salads. There will be little seed hulls in the jar. I grab a bunch of sprouts in my hand and run a little water over. That rinses away lots of the hulls. I don't worry about what's left - they are fine to eat. I store the sprouts in the refrigerator.
If you are interested in learning more about sprouting, the Sprout People website has a ton of helpful information.