Totally depends on the damper and even the temperature. Start LOOSE! Too tight and you'll fall over the first time you pull into a gas station and have to wag the bars in a tight spot, haha.
I like to start at zero and keep turning it up in the garage until I can start just to feel resistance when i go lock to lock, that would be my minimum setting. You should not have to fight it or even notice it at all when you are normally riding.
Since it's the most noticeable at very slow maneuvering speed... go do a slow, tight, slalom. If it feels fine, turn it up, if it feels uneasy turn it down. Keep doing that and you'll probably leave it at that setting forever. I REALLY like having mine on and it helps a ton especially when the front tire starts to square off and you feel like the bike falls into corners and you have to catch it to stay up. This solved that for me.:applause: