It has always been that the Refs give the "ready" signal to the kicking team. They can't kick it off before then. In fact, if they do, the Refs blow the whistle, stop the play and order a re-kick.

Has that changed?

Because in the end the Head Ref said that they had NOT put the ball into play.

I can't imagine a rule that let's the kicking team quickly run out onto the field, refs not saying they're ready, and they just kick the ball while the other team is still mostly in a huddle.