These days, it is the practice of many to learn a folio of the Vilna printing of the Talmud each day. Where did this custom come from? When?
b) When the Daf Yomi was started the Vilna printing was not the only popular print in use and the signs that announced where folios were to be learnt and when included references to both versions of the Talmud.
Tovia Preschel (Mamare Tovia, vol. 2, p. 59) quoted a source which states that in 1908 the Gerrer Rebbe requested of his followers that they designate a specific time in the day so all followers in different lands could be joined in Torah study. It’s quoted there that he added, “perhaps it’d be a better enhancement to suggest that when studying convenes at the designated time all the participants study the same page of a particular Tractate.”
According to the dates given on Wikipedia, it would appear that the Gerrer Rebbe’s idea was the earliest “Daf Yomi custom” though not a organized national movement.