Did the passing of time come before everything else? As in, how long was there "nothing"? And if we can put a time on that, wouldn't time itself be something? And if so, is time the thing that "always was, always is and always will be"? Will time always exist, even if there was nothing else out there? I feel like it would have too. And is it possible for time and space to be the same thing? Like could time, space, and distance be the same thing? My brain is exploding thinking about this and I don't have the first clue about any of this. So forgive me if I come off as stupid. But it seems to me that time would be the thing that allows anything else to exist.
There are three common models for time, and they give very different answers to your question. They all also all have apparent refutations, so -- welcome to philosophy!!!!
The most common model for most of history was to treat time as just a convenient metric to refer to sequential state changes. This is often called the "A" model of time, or Presentism in philosophy. In this model, "time" doesn't really exist -- it is an invented concept by us to refer to the history of state sequences, and to project future state sequences. The only things that actually exist are the things of the universe, and they only exist in their "present" state -- hence"presentism".
The more common model among physicists today is Block time, or the "B" model of time. This model treats time as a dimension of a 4-D Space-time continuum. This is Einstein's model behind General Relativity. In Block Time -- the past, present, and future all have the same status -- there is no special feature to the present. And the future is already set.
A third model is Growing Time -- which treats the PAST as in Block time, but the future does not yet exist. The present has a special status as the edge of Growing Time. Growing time was developed as a "fusion" model -- an effort to find away to incorporate the best features of Block time and presentism in a better model.
Here are several books by active contemporary physicists, arguing for each of these three models of time: https://www.amazon.com/Now-Physics-Time-Richard-Muller/dp/0393354814/ref=sr_1_2?keywords=now+book+time&qid=1579967482&sr=8-2 https://www.amazon.com/gp/customer-reviews/R16VWWZ5I5SC8Q?ref=pf_vv_at_pdctrvw_srp. https://www.amazon.com/Brief-History-Time-Stephen-Hawking/dp/0553380168/ref=sr_1_1?gclid=CjwKCAiA66_xBRBhEiwAhrMuLS7QxrEpXtl3TQz0U8hE_wcs5zI3JS_VA-5BwV4O7LEfxJDL0kbPhBoCxxEQAvD_BwE&hvadid=409937897484&hvdev=c&hvlocphy=9007826&hvnetw=g&hvpos=1t1&hvqmt=e&hvrand=1011146611814977205&hvtargid=aud-836718182849%3Akwd-24482383&hydadcr=24633_11410104&keywords=brief+history+of+time&qid=1579967433&sr=8-1
These books provided fairly criticisms of each of their competing models of time. Summarizing the critiques:
Block time provides no explanation of our sense of the present -- a theory of time which fails to predict or usefully understand the primary feaure of time -- is a remarkabley weak "theory".
Block time advocates generally assert that our experience of time is an illusion, and call for us to dismiss primary experience in favor of theory -- which is explicitly anti-scientific.
Block time is in conflict with all indeterministic models of Quantum Mechanics (which is most, or arguably all of them).
Presentism appears to be in conflict with actual physics, in which all events and interactions have duration -- an infinitesimal approach to time's extent -- cannot usefully address how our universe seems to be coupled into longer periods than an instant. This problem is referred to at the "thickness" of the present.
Block time is very useful in both relativity, and in modeling the outcomes of QM interactions, while presentism cannot support either. Using the "indirect inference to reality" model of science -- this is strong evidence for block time over Presentism.
Growing time gives the present a special status, adressing one flaw of Block time, but in growing time the present is absolutely SECONDARY to the past. But we don't seem to be able to interact with the past -- and the present seems to be far far more important than the past -- so a model that declared the inaccessible past to be "real", and the present is special in only a minor derivative way -- is still not a particularly useful model, and it too is contradicted by immediate experience.
Growing time also does not address the "thickness" problem for an instantaneous present -- the past/future boundary in Growing Time cannot have dimension or "thickness".
Under Block Time, there isn't a "before" either time or space, both appear or not, together. Under Presentism, time is just an arbitrary logic attribute of prior states, and logic pre-exists matter and matter states, so "time" would be first. Under Growing Time, only past time exists. Whether the universe is independent or not of time, and there could be a "before" is unclear, the model needs further development.
However, given that each model has falsifications of it, another way to summarize the status of a "first time" is -- we don't have a good model, so we don't know how to answer your question.
In absolute sense there is nothing called Time. Time is an illusion. The term, 'Advaita' (Non-dual) itself denies even the slightest difference that might arise when we say oneness; since there must be a second thing to say oneness. 'To experience advaita' in this life itself is possible; assures this vedanta. Then, as you mentioned, there must never be two here it this vision; in the case of time and space also.
These two links explain the answer to your question:
From a physics standpoint, the passing of time came with everything else; it began with the Big Bang. Space and time are not the same thing and cannot be treated on equal footing when describing spacetime because it is possible to freely move backwards and forwards in the three dimensions of space but you cannot freely move backwards or forwards through time.
The relationship between the beginning of the universe and the beginning of time is dealt with in any college-level astrophysics description of the Big Bang. This forum is the wrong place to go into this in detail but there are a number of book-length popularizations of this topic that are available for non-physicists. Chief among these is A Brief History Of Time by S. Hawking.
The concept of Nothingness is in high level of self-awareness. You can identify nothingness with Consciousness. So the true undrestanding of Time must be described by Consciousness. Space-time is the lowest level of reality. Space-time-Consciousness is high level of reality.
Don't worry if your head is exploding, time is one of the most vexed topics in philosophy and physics, not to mention psychology and theology. The problem dates all the way back to Heraclitus (all is flux) and Parmenides/Zeno (all is one) and is famously addressed by St. Augustine: "What is time? If nobody asks me, I know; but if I were desirous to explain it to one that should ask me, plainly I do not know.” (So reminiscent of Justice Potter on pornography!)
It is useful to remember that time, by one standard, is a formal measurement of durations by some means of constant repetition, and that this was crucial to the development of modern physics. Galileo had no stopwatch and "timed" pendulums using his pulse. According to Mumford the standardization of mechanical time and timepieces evolves with ways to call the hours for prayer in Western monasteries, coupled with chimes and eventually village clocks.
But what is time really? You may want to read a brief introduction to Einstein's special relativity and Minkowski's "spacetime." Then, by way of contrast, a brief description of Bergson's concepts of living or biological duration.
One famous description in philosophy is J.M McTaggert's distinction between "B Series" as immutable relations of things happening "before" and "after" one another. Then "A Series" time is the same series with a designation of "the present." He famously uses this to prove the "unreality" of time, but this is all pretty obscure and outmoded now, I believe. Yet is is a useful distinction to read up on.
The problems of time reach into the works of nearly every major philosopher, so there is really no "getting to the bottom of it." Speaking of which, it's interesting that your question about "before" time seem to be itself as old as time, with propositions appearing in so many creation myths worldwide.
As in Genesis, it is often seen as an infinite regress of "chaos" giving way to acts of serial, then exponential division. Not so different in basic storyline from what physics tells us around the campfire today.