According to Chris Haynes of the Northeast Ohio Media Group, chances are 'slim' that Irving will be ready to play on opening night against the Chicago Bulls and that he may not be ready to play until January. After Irving fractured his kneecap and had surgery, he was expected to recover in a 3-4 month time frame. According to Haynes' report, the goal for both the Cavs and Irving is to have Irving come back without any setbacks and have him ready to go at full strength when the playoffs start.
This marks the first time that Irving's recovery timeline has been updated with specifics. In early July, Irving appeared on Shaquille O'Neal's podcast and said that he would take his recovery slow while calling the injury the 'hardest thing he's ever had to deal with'. In late July, Irving was cleared by doctors to begin working out and was able to start putting pressure on his leg again. At that time, Irving told the NEOMG that he would not be putting a date on anything regarding his return.
Not having Irving back by the beginning of the regular season wouldn't be the end of the world. The Cavs still have LeBron James and Kevin Love - who will be returning from his own season-ending injury - and signed Mo Williams over the summer to backup Irving. They could get by.
A January return, though, would mean that Irving's injury kept him out for roughly seven months - almost double the expected amount of time - and while the Cavs do play in the weaker conference, playing a few months of basketball without one of the team's three best players isn't ideal.