Thanks to the "inspired expressions" of the FDS/GB of Jehovah's Witnesses, not only are 99% of J.W.'s excluded from the new covenant, but apparently none of the first century Christians are part of the "Israel of God" - aka "spiritual Israel."
w14 11/15 p. 26 par. 11 "Now You Are God’s People" "In 1919, Jehovah delivered them, making a clear distinction between them and "the weeds," or imitation Christians. He gathered "the sons of the Kingdom" into an organized people, in fulfillment of Isaiah’s prophecy: "Will a land be brought to birth in one day? Or will a nation be born all at once? Yet, as soon as Zion went into labor, she gave birth to her sons." (Isa. 66:8) Zion, Jehovah’s organization of spirit beings, brought forth her spirit-anointed sons and organized them into a nation."
ip-2 chap. 27 p. 398, 399 par. 16 Jehovah Blesses Pure Worship "In 1919 this "woman" rejoiced to see the birth of her anointed sons on earth as an organized people, "a nation."................."By the autumn of 1919, they even announced the publication of a new journal to complement The Watch Tower. Called The Golden Age (now Awake!), that new publication was evidence that God’s people were revitalized and once again organized for service."
I always thought that the "Israel of God" came into existence in one one day, back at Pentecost 33 C.E. - according to Acts chapter 2.