The recovery time for arthroscopic surgery is 4-6 weeks. You remember Jeremy Lin wasn't able to show up in week 5 of his rehab but, then, that would have been from zero to playoff basketball. Dirk heals from ankle injuries in the time you and I heal from paper cuts, but he's getting older. So let's say 5 weeks.
Today is October 10th. Five weeks from today is November 14th. If Dirk got surgery today, he would come back for the 9th game of the season, against the Washington Wizards.
Remember, we're not making that decision today. Dirk treated this successfully last season (so successfully that Carlisle, unfairly, blamed it on his being "out of shape") with rest and rehab. But since it came back, he clearly didn't treat it 100% successfully.
What surgery would mean for Dirk and the Mavericks
Mavs Moneyball | Oct 10