Without delving further into the debate about Archbishop Lefebvre saying the New Mass (I never thought he did, but even if he did at one time, that wouldn't change my opinion of him), this is the timeline I recall learning over the years. I think M. de Lugo is mistaken about this.
Yes, clearly I should have chosen the word "mandated" instead of "existed." Apologies.
Nevertheless, this does not avail those embarking upon the Operation Rescue of Msgr. des Lauriers, because the veracity of his delusion rests upon:
1) The dishonest notion that Msge. Lefebvre was so enthusiastic for the Novus Oro, that he voluntarily embraced it even before it was mandatory;
2) That Msgr. des Lauriers later changed his timeline when confronted by this actual mandated date;
3) That none of the witnesses he identified supported his claim;
4) And that even to reduce Msgr. des Laurier's claim from dishonesty to mere mistake presupposes that he considered the 1961-1967 transitional Missals to be Novus Ordo.