That makes sense. So, assuming that the original Ocean Palace incident happens on Time's "first run through", lets add something.
On the first run through, time travel to the future can occur without "pushing" up Time Error to a higher value.
So if everything happens in Time Error 0, lets add an event and say it was also apart of Time Error 0.
During the Ocean Palace incident Gaspar, Belthasar, Melchior, Janus, and Bill (a palace worker) are all sucked into time gates.
Lavos first targets Bill, and then the others in the order that we see in the game.
Bill is sent to 1000AD.
So does Bill see Melchior appear from the same gate moments later? or is there a timeline where Bill lives out his life never seeing Melchior?
If its all at Time Error 0, Bill should see Melchior. If not, things are different.
For my example in an earlier post, I'm hoping that Bill will see Melchior.
A similar question would be: If Magus was immortal, would he see Melchior appear from the gate 400 years later?
If so it means that you can see other entities time travel as long as its within the same Time Error....
EDIT: added the following...
Okay, so I think I'm confused about something.
Say we have two entities, A and B
A - at Time X, Time Error Y, travels 10 years into the future.
A - at Time X+10, Time Error Y+1, will appear, of course.
B - at Time X+1000, Time Error Y+1, travels 989 years into the past.
B - at Time X+11, Time Error Y+2, will appear there.
When A first travels to the future, he will not see B a year later in this time cycle. Once time cycles again into the next Unit of Time Error (2), A will see B one year later. Also, for B at TE = Y+1, A will have always appeared at X+10.
So by conventional thinking, the above model shows that my idea of the Black Omen being from the future does not make sense.
If its from the future, there must be an intermediate timeline, as chrono eric suggested, before the Omen would be visible to Crono in 12000BC.
But let's try this:
Crono - at Time 2300AD, Time Error N+100, is now in the future to get the new Epoch. Some years later on this timeline...
Black Omen - at Time 23XXAD, Time Error N +100, vanishes, bound for the past. But before that....
Crono - at Time 2300AD, Time Error N+100, vanishes, bound for Antiquity via Epoch. (12000BC) Resulting in.....
Crono - at Time 12000BC, Time Error N+101, appears in Antiquity.
Black Omen - at Time 12000BC+ X amount of time, Time Error N+101, appears in front of Crono and Co.
When Crono defeats Lavos and creates a new future, the fact that he travelled in the old future to the past is preserved through TTI, even if all of that information has now been replaced. A future Omen would work the same way. Even if Crono time travelling first would "push" Time Error, the entire timeline will play out and come full circle for Crono's arrival - preserving any time travelling done by anyone (or thing) after him.
If something leaves the timeline at the same point on Time Error as you, and then reappears on the same Time Error point you reappear on, but AFTER you on the timeline, you can see their entrance.
If you think about it... look at what happens when Marle goes into 600AD at the beginning of the game:
From the 600AD onward, the timeline should be discarded and there should be a new timeline where Marle is never born in 1000AD.
But that isn't what happens -- the old 1000AD and onward still plays out. That means we are still in the same Time Error. Even crazier is that Crono time travels from there! That means, from Marle's perspective, Crono eventually comes for her. There is no Marle who lives out her life in 600AD to old age, or even a 600AD where the Queen is never saved.
Now, the game conveniently gives the opposite perspective. While the player is in 600AD, Lucca travels into the past, changing the timeline yet again, but still there is no Crono who lives out to old age or one that rescues the Queen on his own. All 3 of them travel from the same point on Time Error, and end up on the same point because each one travelled/arrived after the other and the timeline continued to run its full course before resetting.
In conclusion, it is possible for the Black Omen to have travelled from a very distant future to the past, appearing in Antiquity X amount of time after Crono and Co.