I had acute onset of PN symptoms, mine was caused by prediabetes & low b12.
I wouldn't have a clue how long i was in a prediabetic state, maybe years i was damaging my small fibres nerves before they were really damaged which of course brought on PN symptoms, with like eletrict zaps, intense burning, and numbness on the soles of my feet.
That was roughly 4 years ago, i went off all high sugary carbs, eat a sensible diet, some exercise in the local pool [ non weight bearing] lost a fair bit of weight and have successfully reversed the prediabetic state, i very seldom get any burning, probable once in a blue moon no more zapps or anything elseassociated with PN.
Prediabetes can be reversed and nerves can and do regenerate once there in the right enviroment, but they do take some time.
good luck
Brian