With a small correction, your hypothesis holds perfectly, and resists the criticisms which are made of it. This small correction is: « Is it possible that the time of a conscious mind is only in this mind? ». Time is relative. It is experienced personally. We all have people around us whose thoughts seem to be faster or slower than ours. We evolve in different times, connected by communication. Each of the phrases pronounced is in the past of someone else (if we are the receiver) or in his future (if we are the transmitter).
This relativity of time takes root in every level of organization of reality. Our unconscious concept factory is in the past of the conscious. An insect or a bacterium evolves with representations (their specific reading needle) that take into account minute events, imperceptible to our senses. Their time is considerably accelerated. Acceleration does not mean shortening the represented temporal set. A proton “experiences” an eternity of time agitated by the ballet of its elementary fields.
Physically, time is an emerging property of a quantum level of reality. It “classifies” interactions with “before” and “after” in the same way, for example, as the electricity property increments or decrements the voltage in a conductor. The process of our mind being a succession of biological interactions, it is intrinsically based on time, to the point of having a considerable difficulty to shift from it in order to define it.
However, I do not know if you have understood the implications of this hypothesis. This makes reality a fixed tapestry for “someone” situated before the emergence of time (in the quantum vacuum?), But a tapestry formed of all possible and not just “our” reality. “I” becomes a set of interactions, a “thread” within this tapestry. The sensation of passage of time is the coordination of a multitude of neural interactions, forming a vast scheme. There is an order within these interactions. Not all diagrams are possible. But an incalculable number of them is possible. The diversity of “I” within this tapestry is incommensurable, within a even less measurable diversity of universes. The one you are experiencing is a tiny iteration.
So that the universe is not more fixed than before by this hypothesis. Possibilities are always numerous, what we cautiously summarize in the term “random”. Time continues to carry us, we do not know where, for the process experienced as “I” does not have the means to get away from it to contemplate the tapestry and predict. We can just imagine at leisure what we could be. Now “to imagine”, in this hypothesis, has as much reality on the tapestry as the rest. That is to say that these thoughts are indeed constitutive of the sequel. Hurry up to have them if you want to “be” your destiny!