The time decide is only one factor though. There's the time it takes for the VAR to check to advise an incident has occurred. And that doesn't factor in cases whether the ball doesn't go out. So play has to be called back etc. There was a case in the CWC similar to this.
This was the incident. https://twitter.com/Dale_Warburton/status/80932675...
Ref halts the start of play, clearly because the VAR is still checking over a minute after the event.