If you were a pony in Equestria and you could go back in time...

[Osiria 142]

If you were a pony (probably a Unicorn/Alicorn since you need to cast a spell), and you found a spell that allowed you to go back in time for a few days or even longer....

 

There are so much fun to do!   Build Ponyville with filly Granny Smith (Maria Apple Smith?), learn more spells from Star Swirl the Bearded, join the E.U.P guard and meet General Firefly, or help three tribes found Equestria (then you can tell everypony "that's how Equestria was made") . ...

 

For me, I would go back to thousands years ago, hang out with filly Celestia and Luna. And maybe (just maybe 'cause it would change history majorly) prevent Luna from transforming to Nightmare Moon.

 

 

Where/when would you go?

[Rainboom Dash 1,056]

I would see how the three tribes founded Equestria, and maybe visit filly Celestia and Luna too.

[Bird Mom 900]

I would end up eating old timey food. Is that bad? ^ - <

[Neutral 1,185]

I would go for when the heart for the crystal empire is to be protected and just steal it and give it to king sombra.

[~Sassy Dashie~ 712]

I would visit Filly Celestia and Luna as well, then I'd find out how Cadence came to be how she is today.

[Leonard Smix 421]

COMMANDER HURRICANE HERE I COME!

[ThatOneComrade 1,091]

I'm gonna say medieval times prior to the sisters sucked so I'd probably check out how things were afterwards, you know? See the sights, see how/why Luna and Celestia were crowned. Maybe prank Celestia and go back to the future just to mess with her when she sees me again. 

[Sekr Gray 520]

Being the history buff I am (pony history and non-pony history), I'm gonna have to go with the Medieval Ages, prior to the Princesses, like in Hearth Warming's Eve. All that history to see and document! 

 

... I have issues.

[Will Guide 21,362]

I would go back to whenever Spike's egg was laid. Actually witness Spike's parents meet. See if there is SOME small possibility that a baby dragon can mature without having to possibly succumb to greed. If it turns out that my trip is what brought Spike egg to Celestia before it was brought out for Twilight's Entrance Exam, I'll play my part.

[Denim&Venöm 19,203]

Back before dawn of time, so I can see how all of existence began. 

[Mouse 302]

I'd probably go back to Cloudsdale when Rainbow Dash and Fluttershy were fillies, and (as a young colt) hang out with them and fight those big meany poopy bullies.