Many moons ago, Riot talked about potentially releasing an earlier surrender option into the game and lead champion designer Andrei “Meddler” van Roon has confirmed that this feature is still being worked on.
If all five teammates of one team agree, there could be a potential option to surrender at 15 minutes, instead of 20 minutes.
Unanimous surrender (5/5) at 15 minutes is the version we were looking to test. That slipped as a priority relative to the new client and pre-season work. We'll be getting back to it soonish most likely though. Probably going to start off with a test on one region only, then assess whether it's working as intended or not and whether we should roll it out wider.
This feature could be pretty helpful, especially when it comes to tilting games that go sour early. However, some players on the boards are concerned about potential abuse. For example, if a premade of four no longer wants to play, it could pressure the final player into surrendering early by being toxic, although that’s not terribly different than what could happen now with the 20-minute system.
There is no other update on how soon it’ll be until the early surrender shows up on specific regions, but now that those big updates are out of the way, we can expect to see it sooner than later.