I don't think that St Athanasius can be used to clarify St Cyril. The words of St Cyril must be used to clarify St Athanasius.
As far as I can see, from the earlier discussion on the heresy of the Agnoetae who denied that Christ had all knowledge in his humanity, there was no time when Christ was not omniscient, though this was not manifest.
The holy soul of the Word possesed the entire knowledge of the Word whose soul it was, for the entire will of the divinity is in Christ, as Athanasius, who is with the saints, taught.
Anthimus of Constantinople says..
For us, however, there is one hypostasis and one nature of the Word of God incarnate, just as there is without doubt, one will. And we know only one operation and one wisdom, and one knowledge for both. Therefore whoever says that he knew as God, but as a man, however, did not know, unsuitably divides the one indivisible Son into two natures, and two hypostases, as did the impious Theodoret. But we, by the grace of God, believe, as we have already said, the divine soul, rational and intelligent, consubstantial with our souls, had, by the union with God the Word, an existence with his body, consubstantial with our bodies, and from that union, it has gained all its operation and wisdom, and divine omniscience, so that there is one and the same knowledge of God the Word, and of the intellectual soul.
Maximus the Confessor says..
If, then, among the holy prophets, things which were at a distance and beyond the scope of our power were recognized through the power of grace, how much more did the Son of God, and through him his humanity, know all things - not of the nature of that humanity, but through its union with the Word. Just as iron in the fire has all the properties of fire, since it both glows and burns, yet in its nature remains iron and not fire, so too the humanity of the Lord, in so far as it is united with the Word, knew all things, and displayed attributes proper to God. However, in so far as his humanity is considered as not united to the Word, it is said to be ignorant.
And St Cyril and St Severus say the same, though it is early here and I have to pop out so I can't post more now.
As I said, I believe that the Fathers teach that there is a growing manifestation of knowledge and wisdom, but that Christ always has all the knowledge and wisdom of God as being the humanity of the Word. The position that Christ was ignorant is that of the Agnoetae and is condemned.
I am wanting to avoid arguing about words however. Yet I do sense a difference of view. How would you think your view is different from that of the Agnoetae?