Teen Titans formed before the Justice League in this continuity?

By the time we see Dick Grayson in Son of Batman (which came out April 2014), he's already Nightwing. That's also the movie that introduced Damian Wayne as the new Robin, which suggests that Dick has been Nightwing for a while.

In Justice League: War (which came out January 2014, a few months before Son of Batman), we see the heroes not only meet each other for the first time (with possibly being aware of each other beforehand), but forming the Justice League that very night.

Now, in a recently released clip from the upcoming Teen Titans: Judas Contract, we see what is presumably a flashback of Dick (as Robin) and the other sidekicks saving Starfire. We can assume that not long after that the Teen Titans formed up, if they hadn't already done so, since it's inferred that they've been together a while by the time Justice League vs Teen Titans came out in 2016.

Here's the clip for those who still haven't seen it:

https://www.youtube.com/watch?v=CfDrWQTwZlY

So back to my question, did the Teen Titans form up before the Justice League? If so, it's just a little weird that the sidekicks thought up the idea to team up before their mentors did, and then the mentors act like it's a surprise meeting up other heroes in JL:W like it hasn't been done before.

When the whole world tells you to move, you plant yourself like a tree and say "No, you move"