Was thinking about how MLP used Time Travel in its narrative and how Starswirl's Time spell is technically self correcting. Putting that aside, the real question is, would the episode "The Cutie Re-Mark" still happen or be similar?
Since Twi and friends could handle Starlight differently resulting in said episode never happening. Or since there is no real single moment of them gaining their Cutie Mark(Someone can always write one), Starlight would have to evaluate what event she would alter. So the question would be when and what could result in her interference?

The thing about that episode was that with every change in the past a new future was mold but only in one timeline since this was not a Multiverse theory every change happened in one universe.

Also, many don't know this but, since Twilight had the scroll with her Statlight never was aware of the changes but she was still aware when Twolight went back in time with a failsafe.

What I am getting at here is that there will be a Starlight but not a time traveler one.

Yay Time travel, it is very confusing especially with different interpretation of said method.

I was thinking how the episode "It's About Time" was a perfectly loop creating a Boot Strap Paradox. Then to "The Cutie Re-Mark" Where it can be seen as alteration to the timeline. Or as a possible example of multiverse theory, With reason just that Twilight and Spike not just creasing to exist once Starlight went back. Though the Marty McFly delay/Paradox can explain it too.

The Whole self Fixing is based on Futurama "Bender's Big Score" and other Time travel centric media where the traveler can't alter history beyond what can happen. Heck "The Cutie Re-Mark" Technically had it that since the Table did send Twi and Spike back to fix it. Preventing a Grandfather Paradox.
Then I thought if there was change that could occur that would result in that never happening. Be it Twi never using it to warn herself and creating an Paradox of timelines and future selves.

I think I thought about this too much.

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Time travel is not about When but the How; most things about this comes from how many fans of Dr. Who see this, but I think that Time travel os nog the change of timelines but the adaptation of the circumstances... after all things can go however you want and no one will notice this. Except for the traveler.

Starlight could either stop Twilight from passing her entrance exam at Princess Celestia’s school or tamper with her friends lives.

Thought back on this.
It could happen when, Either when Twi becomes "Friends" with everypony, or when Twi was about to go to Ponyville. I like to think on the latter one that When Twi and Spike get flung back to present that they're in the main timeline of the show. How confused would Twi be when "those ponies from Ponyville" are the Holders of elements of harmony. Like sure she may recognize them, but sure won't understand how they became the holders. Twi may actually stay in that timeline for a bit longer to figure it out. Finding those Friendship books or her Other's notes. Seeing how they handle those situations compared to her friends.