"The finger is very stiff right now, but the good thing is I am pain free," Iwakuma said through translator Antony Suzuki on Tuesday.
Manager Lloyd McClendon said Iwakuma would start slowly by throwing tennis balls on Friday, Saturday and Sunday.
If the right-hander doesn't experience a setback, he could begin throwing baseballs on Monday. Iwakuma, who finished third in American League Cy Award voting last season after posting a 14-6 record and a 2.66 ERA, is looking forward to returning to the field after missing more than a month.
"It's hard to say being in my situation right now," he said. "I want to come back soon, but I don't want to push it and have any more setbacks. It's a long season and I look forward to finishing strong. That's all I have in mind."
Information from the Associated Press was used in this report.