I'm just about as light skinned as you get, without being a ginger or albino. I used 500mcg every night for 40 days, tanning bed for 8 min once a week, and I saw within the first 2 weeks a noticable darkening of my skin. I know that it's not quite summer yet and the gen pop hasn't had time to get the dark beautiful tans yet, so as of right now I'm pretty evenly matched compared to people I would normally look albino standing next to.
As you've probably already found in your research of this product, it does make freckles appear that you otherwise wouldn't have known to exist.
Not sure if that helps or not, but that's my success story...