Thomas, who was acquired from the Boston Celtics in a trade for Kyrie Irving last month, suffered a torn labrum in his right hip last season, which eventually caused him to sit out the last three games of the Celtics' loss to the Cavs in the Eastern Conference finals.
"Physically, I'm in a good place," Thomas said Monday. "I'm making progress each and every day, I'm getting stronger."
"Isaiah Thomas has successfully continued with the rehabilitation process related to his right hip impingement," read a statement released by the Cavaliers on Monday. "Based on his progress thus far, and after several weeks of evaluation and monitoring with the Cavaliers medical team and Cleveland Clinic Sports Health, the team and Thomas are hopeful he will be in position to return by January. His status will be updated again, along with any further timeline adjustments, after the start of the regular season."
Thomas' timeline means a possible debut with his new team on or before Christmas Day, when Cleveland faces Golden State in an NBA Finals rematch.
"That's the plan," Thomas said of returning by January. "I'm excited about that. I feel like we've been making a lot of progress these last three or four weeks.
"I can't wait to get healthy and be able to be 100 percent and help this team win a championship."
Coach Tyronn Lue said Derrick Rose will be the starter at point guard to begin the season. Cleveland will also look to point guard Jose Calderon. LeBron James will be tapped into for his ball distribution skills as well.
Thomas' rehab has included hip mobilization exercises, running on an altered-gravity treadmill with less than his full body weight and pool workouts, as well as on-court basketball activities centered around shooting, sources said.
The Cavs medical staff's approach to Thomas has been led by Dr. James Rosneck, a renowned hip specialist practicing at the Cleveland Clinic. The team is also consulting with Dr. Bryan T. Kelly out of New York's Hospital for Special Surgery. Kelly treated Thomas when he was still with the Celtics.
Thomas was advised by the Celtics to take three months off following the Eastern Conference finals to heal the hip, and the inactive recovery plan did not bear many improvements, sources said.
Since adopting the Cavs' plan -- which includes a nutritional approach -- Thomas has made gains both physically and mentally, sources said, as he has experienced positive results.
Thomas' rehab has gone so well the Cavs have had to urge him to be patient with his eventual return date, sources said, as the team is hopeful it will make a fourth straight trip to the Finals and need him well into June. The team is also ruling out surgery as an option for Thomas, sources said. However, they could explore a more radical treatment option such as a platelet-rich plasma injection into the hip as time goes on.
Thomas averaged 28.9 points, 5.9 assists and 2.7 rebounds per game last season for the Celtics.