Kerviel's feet are already bleeding as he passes through Tuscany, friends say.
"He has a few possessions and practically no money," his lawyer David Koubbi told the 20 Minutes free paper.
He intends to sleep in people's homes and walk 15-30 kilometres per day, meaning that he will not be back in Paris on 19 March when a court will rule on his appeal against a five-year sentence, with two suspended, and an order to pay 4.91 billion euros in damages.
The Pope agreed to meet Kerviel in a traditional encounter with several of the faithful after a general audience on Saint Peter's Square and is reported to have been "very affected" by a letter the trade sent him.
Kerviel, who says his employer, Société Générale, encouraged the risk-taking that led to his downfall, says he is seeking divine justice after being disappointed by human justice.
He has called for an independent experts' report on the amount of losses that bank suffered.