How much B12 to take?

I've just been diagnosed with mild peripheral neuropathy and my only symptoms are numbness in the balls of my feet and toes with a smal amount of tingling and burning. I have no pain. After reading your website I bought some B12 as you suggested and started taking 3 mg a day. The tingling and burning went away almost instantly but the numbness is still there. It's only been about a week, but how long should I wait before I increase to 4 Mg, then 5, etc. and when should I stop increasing?