If I remember correctly the doctors said he'll be back this season.
He was injured on 16th September, so almost 5 months ago. If there are no complications it usually takes 6 months to fully recover from knee injury. I think he'll be ready to play end of March/start of April, if we don't rush him back. Which there is absolutely no need to do. He's a young player with great future ahead and the last thing we need is for him to become injury prone like his brother seems to be.