Zeir Anpin is then described as being in fixed possession of Netzach-Hod-Yesod, while the others still need to be revealed in actuality. This should be clear in the light of what I have written.
The entire period of Pregnancy is a process of gradual preparation little by little to enable Chessed-Gevurah-Tiferet to be revealed. Zeir Anpin possesses Netzach-Hod-Yesod immediately but this is not to say that they are complete, for to be complete they must have Chessed-Gevurah-Tiferet revealed over them. The entire period of the Pregnancy is a process of preparation towards this. The reason is because it is impossible for there to be any less than Netzach-Hod-Yesod, and we must therefore say that Netzach-Hod-Yesod are present from the start of the Pregnancy, even though they are not complete until its end. During the Pregnancy, Netzach-Hod-Yesod are steadily prepared to receive Chessed-Gevurah-Tiferet at the time of birth.