Pony General:"Season 12 will never air" edition.

 Not much of a spoiler but still

So industrial revolution is now confirmed?

 Spoiler

Amusingly, I don't think I can think of anything that can refute that idea. We haven't seen a form of a TV yet, so definitely before the 30s. The fact we saw some Steam Punk-esque stuff, probably early 1900s. I now wonder if the community as a whole has thought about this, although I'm very sure they already did.

Upon looking though, I realized that the most modern technology that they seem to have is DJ-P0N3's DJ player, which is somewhere around the 30s-50s according to Wiki. So final date would be somewhere around there. Inb4 computers and TVs start popping up in later episodes.