By tradition, when does the presidential campaign begin?

By tradition, the Presidential election begins after a candidate is officially nominated at the national convention. Before the candidate is officially nominated at the national convention, he or she can unofficially continue the campaign process, but it would be of no importance if he or she does not get nominated in the national council. It is a tradition that after the completion of the national council, the selected candidates start their campaign from the month of November. It has been seen that several candidates start seeking money for the campaign long before the completion of the national convention.