Re, your question:
You write, “In the beginning, there is nothing—infinite, eternal, 100% emptiness.”
A few concept-corrections. What is nothing, does not have a beginning (nor an ending). Infinite, eternal, 100% are qualifying descriptions. No descriptions have anything to do with what is nothing: even to say “exists,” or “doesn’t exist,” is to go too far.
Nothing (ness) does not make an appearance as…(anything). Appearances have to do with ideas concerning time and place—which are only within the dream.
Yes, within the dream, there do appear to be appearances—“something(s).”
All of these appearances—all that we see and experience—have always been empty (of “reality”). Emptiness, or nothingness, did not at some time catch up and overtake them.
In other words, their true nature is (always already) empty of reality.
These things, or forms, are impermanent. When one ceases to be, it does not disappear and its emptiness go somewhere. When there are no appearances—seer or seen—there is no emptiness. It has no “existence” or “nonexistence.”
So, appearances are empty of supposed reality. Emptiness is what they are. That they are not real, in the first place, is how they “cease” to be. But they never actually “were.” That is why they are “empty.” And that is the “explanation” of emptiness.