Quintana underwent the surgery on July 2 after slicing his left thumb while doing dishes at home on June 27. He recently started long tossing from 90 to 105 feet.
"The last few days, I have been feeling great," Quintana said. "No pain and nothing bothering me around my thumb. I am lucky that the part where I release the ball, I don't feel any problem in that area. Yesterday I threw fastballs and changeups. It feels great."
The plan is for Quintana to begin bullpen sessions in the next seven to 10 days to build up his arm strength. Until throwing earlier this week, he had been relegated to just doing upper- and lower-body weight training.
"It's a long process when you're coming off surgery in any capacity, especially talking about his throwing hand and what he had to go through with some nerve damage," Ross said. "The good news is he's feeling good. He's got the feeling in the fingers ... There's still a lot of different grips that he's going to have to toy with when he starts to stretch that out. He still has some dead skin under that scar that's going to affect how he holds the ball. Hopefully that falls off in the next few days, or they're able to take that off and put some covering on that for a minute. He's still got to spin the baseball, hold the changeup. All those things still have to come along.
"He's pretty far off, but from where we thought he would be, he's ahead of schedule for us of where we thought he might be coming off a pretty serious surgery."
The Cubs haven't provided a timetable for when Quintana might return. Could he be available for half of the season?
"I hate to put a timetable on something so serious," Ross said. "I'm hopeful like you guys are. Q's a big part of this team. He brings a lot of energy. He's a guy we were definitely going to count on this year for big innings. It's a huge loss. Somebody will step up in his place and pick up the slack, but we're definitely hopeful that we get some significant innings out of him this year."
Quintana also didn't reveal when he might be ready for game action.
"I don't know when I will be available to pitch," Quintana said. "I feel that it's more important for me to feel good building up my arm and body. I know it's too early to say how I will feel throwing in the bullpen. The doctor said the recovery would be hard. But I feel really good the last few days throwing the ball.
"The thumb, as I said, doesn't bother me, so I should be able to throw the curveball in the next couple of days. I will start throwing the curve, so we will see how it feels. I don't have any concerns about throwing the curveball because the thumb has felt well. So far it's great. We will see in a few days."
Quintana, 31, was 13-9 with a 4.68 ERA and 1.39 WHIP in 32 appearances in 2019. He was projected to be the No. 3 or No. 4 starter in the Cubs' rotation prior to the injury.
"I have been staying positive and getting my work in now," Quintana said. "I need to be ready and prepare to get back."
In other Cubs injury news, the plan is for first baseman Anthony Rizzo (back) to be in the lineup in the exhibition finale Wednesday evening, Ross said. That will be dependent on how he feels after his work Tuesday. If Rizzo is in the lineup Wednesday, it would be a step toward him being in the Opening Day lineup Friday.