Here's the scheme:
Earliest possible Pascha:
Sunday of the Publican and Pharisee: Jan. 11 Julian (OS)/Jan. 24 Gregorian(NS)
Cheesefare: Feb. 1 OS/Feb. 14 NS
Beginning of the Fast: Feb. 2 OS/Feb. 15 NS
Annunciation: Falls on Wednesday of Bright Week (Julian)
Pascha: Mar. 22 OS/Apr. 4 NS
Latest possible Pascha:
Sunday of the Publican and Pharisee: Feb. 14 OS/Feb. 27 NS
Cheesefare: Mar. 7 OS/Mar. 20 NS
Beginning of the Fast: Mar. 8 OS/Mar. 21 NS
Annunciation: Falls on Thursday of the 3rd Week of Lent (Julian)
Pascha: April 25 OS/May 8 NS
So the earliest a Pre-Sanctified can occur is Wednesday, Feb.4/17, when
Pascha is the earliest it could be.
Overall, there is a range of 35 days upon which Pascha can fall, from March 22nd through April 25 according to the Julian calendar (April 4th through May 8th, according to the Gregorian). So the Lenten Triodion could begin as early as January 11th with the Sunday of the Publican and Pharisee, and end as late as April 24th with Holy Saturday according to the Julian calendar (January 24th through May 7th according to the Gregorian).