Hi, I can only speak of my particular PN case [ mostly small fibre damage and a little large nerve involvement, severe burning in both feet and up to my knees] which was caused by prediabetes and my b12 was very low, if i was to try to answer as to how long it took to do the damage, i think i could safely say a couple of decades.

Once PN showed its ugly face it took about 4 months before the culprit/s were indentified, then through change of diet and some execise and lots of B12, [some Methylcobalamin, injections of Hydroxocobalamin but mostly cynocobalamin] as we can't buy B12 Methyl' in tablet form in OZ, the healing period took about 3 years to the stage i am in now, which is pretty close to a full recovery.

I didn't notice much differance at the beggining, symptom wise, but after a few months i had a lot of worsening of symptoms, then it would settle down for a while then off it went off again burning like hell then it would settle down for a while, that happened for about 2 years [approx] then i noticed that the flares were getting shorter and fewer in between until now were i hardly get any burning at all, if i do its only very, very slight burning and my soles of my feet were completely numb most of that time but now i have regained a lot more feeling back in them again.

Differant symptoms or flaring of symptoms can be healing signs, i hope it is in your case.

Brian