The 11th of Nissan is the birthday of Moshiach and the 11th of Shvat is the beginning of Moshiach’s leadership in an open, revealed way. * Chapter Ten of Rabbi Shloma Majeski’s Likkutei Mekoros (Underlined text is the compiler’s emphasis)
Translated by Boruch Merkur
8. […] The tenth day of the eleventh month signifies the completion and end of the avoda of refining the last remaining “shirayim – leftovers” of exile, “polishing the buttons.” As discussed above, the avoda throughout the generations is completed and perfected when “eleven” is drawn down into “ten,” but in a manner that they maintain their respective identities (given the limitations of the lower realms). This goal is expressed by the tenth day of the eleventh month. That is, on its own, the level of eleven (“And the L-rd spoke, etc.,” representing a level that transcends the world) does not entirely permeate the world (ten). Thus, there is the chiddush, innovation (chodesh, month) of eleven. However, the revealed avoda (in terms of days, the concept of revealed light) is still expressed at the level of ten (as discussed elsewhere [Seifer HaSichos 5750, Vol 1, pg. 235 ff.] that the avoda of my revered father in-law, the Rebbe, during his life in this world, embodies the revelation of ten).
A further stage is attained on the following day, the eleventh day of the eleventh month. In addition to and following the avoda of the tenth day of the eleventh month, on the eleventh we achieve and ascend to (according to the principle of “maalin ba’kodesh – holiness ascends”) the revelation (day) of eleven, and in such a manner that it also elevates the revelation of the tenth day to the level of “eleven days.” We then have eleven both with respect to the month (the eleventh month) as well as the day and revelation (the eleventh day*); eleven as it is drawn to the mekabel, the receiver (moon, month), as well as how it is for the mashpia (sun, day). However, this is still a level of eleven that relates to and is comparable to ten.
But within this stage itself, we go higher still, reaching a level that follows the completion of the avoda of refining the world as well as “polishing the buttons,” etc., when all that remains is to stand ready to greet Moshiach Tzidkeinu. That is, attaining the perfection of eleven (wholly transcending ten), which brings about the joining and unification of ten (unto itself) with eleven (unto itself), as alluded to in 22 Shvat.
NOTES:
*Footnote 50: To note the connection between the eleventh month and “on the eleventh day (of the first month) the leader of Asher” (Naso 7:72) (according to the opinions that the order of the n’siim in inaugurating the Mishkan follows the months of the year […] The eleventh day of the first month (Nissan) is connected with the beginning of the revelation – the birth – of the aspect of eleven. (See the sicha of Shabbos HaGadol, Erev 11 Nissan 5749 (Seifer HaSichos Vol. 2, pg. 389 ff.)) As is known, the birth of the Jewish people took place in the month of Nissan. … And the eleventh day of the eleventh month is connected with the ultimate revelation of eleven, in a manner of revealed leadership.
(From the address of Shabbos Parshas Yisro, 20 Shvat, and Monday Parshas Mishpatim, 22 Shvat; Seifer HaSichos 5752, pg. 350)