I think the latter part about existence and magical reality juice is a misinterpretation of the OP.
Agreed
By "come into existence", my second-take (i.e. charitable reading because default reading makes me confused) says he's probably referring to the specific moment/state of: "This entity (mind) is aware", i.e. experiences its first qualia.
Actually I didn't really think about that part, but you sir did. I think that this is an entirely different issue and I think this is one way to answer it:
When does the experience of consciousness occur? Is a little misleading question. Instead it should be termed "Which location in spacetime does this arrangement of physics correspond to?" because if you record an experience in some form I wouldn't really say this particular experienience happening at any given time, but it's structure has a causal relationship with other physical structures. If A is the state of a mind and B is a outside physical event, and A and B interact in someway, for an example if a person sees a flower and therefore the state of A changes accordingly, the changes in the internal structure due to the interaction correspond to the event.
In the post the creation process of the conscious experience was left out, in other words the correspondent was also left out, and if there isn't one - then this experience isn't linkable with any specific moment - except if we consider an agent simulating this experience in order to record it then that would be the correspondent for the internal structure of data.
It's a really interesting question though and I'm really not sure if this answer is sufficient.
Ps. Meanwhile the moment when the drawn line came into existence is a different question from the timing of the "experience". Normally though these two things are not distinct I suppose?
This answer is certainly very helpful in clarifying which questions we should be asking. I think figuring out the exact specific questions to ask is most of the solution here, like in maths.
For the purpose of this thought experiment let's assume that the reductionist approach to consciousness is truthful and consciousness is indeed reducible to physics and there is no ontologically distinct basic mental element that produces the experience of consciousness - the qualia.
"The Scary problem of Qualia"
This leads to a very strange problem which I'd term "the Scary problem of Qualia" in a little humouristic sense. If mental experience is as proposed, and humans with brains doing thinking are "merely physics", or "ordered physics", physics + logic that is, then that results to the experience of consciousness being logic given the physics...
...Which is to say that whenever there is (a physical arrangement with) a logical structure that matches (is transitive with) the logical structure of consciousness - then there would be consciousness. It gets more complicated. If you draw a line with a pencil on a piece of paper, so that it encodes a three dimensional trajectory over time of a sentient being's consciousness - you basically have created a "soulful" being. Except there's just a drawn line on a piece of paper.
(Assuming you can store a sufficient amount of bits in such an encoding. Think of a "large" paper and a long complicated line if imagining an A4 with something scribbled on is a problem. You can also replace the pencil & paper with a turing machine if you like)
If you now take a device complicated enough to decode the message, and create a representation for this message, for a sci-fi example a "brain modifying device which stimulates" a form of empathic inference, you can partially think the thoughts recorded on the piece of paper. Further yet you could simulate this particular person inside a powerful AI, even save that information to a disk, insert it into an android, and let that person go and live his/her life on. If this isn't sufficient you could engineer a biological being which would have a brain that produces a series of chemical reactions, enzymatic reactions, combined with an electron cloud etc that happens to be transitive with the logical structure of the data stored on the chip.
Meditation: And this creates another kind of problem. Did the person come into existence:
1. When the line drawn with the pencil came into existence?
2. When the entity that created the line thought of how to draw the line?
3. When the line was decoded?
4. Did it come into existence when the supercomputer AI simulated the person from the line?
5. When it was recorded onto the chip for the android?
6. Or lastly when the contents of the chip were translated to a biological brain producing the same thoughts?
Meditation: Is logic an ontologically basic thing?
In my book this is all a natural consequence from the reductionist approach to the hard problem of consciousness. That is unless we wan't to consider the possibility that electron clouds have little tags which say "consciousness" hanging from.. uhuh.. From their amplitudes.
So in other words: From the reductionist perspective there's just physics which can be described with the help of logic. Whenever there is a physical part of the universe that is correlated with the rest of the universe in such a way that it would resemble consciousness when interacted with, that thing would be just as much a person/zombie as we're. Same goes for simulated people.