If you can stick it in reverse without clashing, then you have enough.
If it makes funny noises, when you depress the pedal,then, either you're pressing it down too far, or you have too much. In between those two, anything is ok. You only have to press the pedal down far enough to make a quick shift. If the shift is slow, the disc may not be slowing down properly, push down a little more. If you can't stuff it into first at a dead stop, it may be because the disc has already stopped spinning and the clutching teeth are butted up. Or more likely, the disc is dragging on the flywheel. Try it into reverse; the answer will be instant clash if the disc is dragging.
If everything is running straight and true, then you don't need hardly any departure. I run about 1/2 inch freeplay, and only press far enough to make the shift, and a little more going into reverse.
If you're running a 3400 B&B, well, you'll be real glad when it comes time to ditch it, and you replace it with a diaphragm.
