He is actually pretty close. I think those first couple games where he made some defensive mistakes got in his head. After that, he played overly safe, and looked a little afraid to be aggressive offensively. That's a sign he's not quite ready though.
Byram can still benefit from junior though IMO, he hasn't outgrown it that much. He can still benefit from working on his defensive play, without sacrificing offense. He's going to play a two way role in the NHL, and it's much easier to work on this in junior, than it is in the NHL at his age.
Playing in the pressure packed WJC and another year in the WHL playoffs/MemCup will be a good learning experience for him as well. I'm actually really looking forward to seeing if he can dominate in the WJC. Realistically though, he'll still be pretty young for that too at 18 still.
Depending on when his season ends, we might even see him get the Makar treatment and sign for the playoffs. Though I think that may be doubtful because I don't think the Avs want to burn a year of his ELC. He's unlikely to contribute as much at 18 as Makar did at 20.