If the Actus Purus of God, the complete perfection, is true, if God has no potentiality, and He was always what He is, then God was a creator from eternity. But God could not be eternally creator if he was not eternally creating. Does this mean that God's creation was eternal?
Many Trinitarian Christians would say that God's character as a creative being is reflected in the eternally begottenness of the Son, even though that does not involve creation. Now there's lots of debate within Christianity about what that means, but it is generally accepted that the Son can be begotten of the Father without being created or made, without being subordinate or lesser than the Father, and can be begotten of the Father while having the same ever-existing singular nature as the Father. There's a sense in which the Son is from the Father which is not symmetrical; the Father is not from the Son or from the Spirit, but simply is. As the Father eternally begets the Son, so it is in character for God to create the universe. Perhaps we should think of creative acts as merely a shadow of eternally begetting, a lesser relationship which creates things which are other to yourself and which come into existence after you.
The Athanasian Creed says:
For there is one Person of the Father; another of the Son; and another of the Holy Ghost. But the Godhead of the Father, of the Son, and of the Holy Ghost, is all one; the Glory equal, the Majesty coeternal. Such as the Father is; such is the Son; and such is the Holy Ghost. The Father uncreated; the Son uncreated; and the Holy Ghost uncreated.
And yet they are not three eternals; but one eternal. As also there are not three uncreated; nor three infinites, but one uncreated; and one infinite.
The Father is made of none; neither created, nor begotten. The Son is of the Father alone; not made, nor created; but begotten. The Holy Ghost is of the Father and of the Son; neither made, nor created, nor begotten; but proceeding.
It depends on your God.
Even ignoring the issues in Aquinas' arguments, even he conceded that his arguments could only prove for a God, not the Catholic Triune God.
Generic Godlike Entity
In the generic case, maybe. Obviously we can't know for sure, but the implication of something that is both eternal/infinite and a creator is that the creation process is ongoing and infinite.
Catholic Triune God (CTG)
In the specific case of the CTG, no. We're leaving philosophy and entering, frankly, Bible study at this point, but it's pertinent as Aquinas' created his arguments for the purpose of the CTG.
According to much of Revelations, as well as the Catechisms, the end times are a literal truth; God is meant to have created time, and will call an end to time. The bell with ring and the curtain will fall, according to the Catholic church.
This is, of course, antithesis to the idea that God's creation is eternal.
Regarding whether actuality could precede potentiality, there is this from Heidegger commenting on Aristotle
Aristotle says this in his own way in a sentence we take from the treatise that deals explicitly with entelecheia (Meta. , 8, 1049 b 5): fanerin oti proteron energeia dynameis estis: “Manifestly standing-in-the-work is prior to appropriateness for....” In this sentence Aristotle’s thinking and pari passu Greek thinking, reaches its peak. But if we translate it in the usual way, it reads: “Clearly actuality is prior to potentiality.” Energeia, standing-in-the-work in the sense of presencing into the appearance, was translated by the Romans as actus, and so with one blow the Greek world was toppled. From actus, agere (to effect) came actualitas, “actuality.”
It seems en-ergeia vaguely means 'in action', but this is taken as good as done (agere) in translation. Not simple to translate these ancient meanings into modern parlance.
In Latin, the fourth principal part of the verb agere, meaning "to do", was actus, which could best be translated as "having been done".