Yes, 6:00 o'clock position and it should be stretching the return spring slightly. The lever should not be traveling past 4:00 when pulled, nor returning past 6:30 when relaxed. The return spring should prevent returning past 6:30 position.
If you have taken up all adjustment room at the lower lever by unscrewing the adjusting bolt counterclockwise as far as it can go, and the cable is still slack when the upper adjustment (at the handlebars) is also unscrewed to its full extent, then the cable is too long.