The Mariners have no firm timetable in place for the return of the man who finished third in the American League Cy Young Award voting last year, but they are happy to finally get his throwing program in motion.
"To be honest, it's been a very, very long five weeks, I can tell you that," Iwakuma said through translator Antony Suzuki. "But the doctor said I could take that splint off and do more with that finger -- the actual rehab -- so that's a good thing. I'm looking forward to that. I've done everything I could for the last five weeks."
Iwakuma will do range-of-motion exercises to begin working on the finger's strength and flexibility for the next few days, then begin throwing a tennis ball on Friday. He'll advance to throwing a regular baseball on Monday, which will kick off the gradual process of building back up his arm strength.
Both Iwakuma and manager Lloyd McClendon stayed away from any best-case speculation on when he might be ready for games. Iwakuma clearly won't be ready for the start of the regular season, which is now less than two weeks away. So he'll almost surely open the year on the 15-day disabled list and shoot for a return in late April, if all goes well.
"It's hard to say, being in my situation right now," Iwakuma said. "All I feel is wanting to come back soon, but I don't want to push it and get any more setbacks. It's a long season, I look forward to finishing strong. That's all I have in mind right now."
McClendon said he has no actual target date in mind. The manager is also juggling delayed starts for youngsters Taijuan Walker and Brandon Maurer. Walker will throw his third bullpen since coming off a weeklong layoff with shoulder soreness on Friday and has been strong since his return, but also needs to progress to live hitters and building up his arm again.
Maurer has missed considerable time with a sore back and just started playing catch again Monday.
"I just need to focus on who I've got here and what I've got available and what I'm dealing with," McClendon said of a possible target date for Iwakuma. "You get caught up in that and you get disappointed. So I don't even think about it."
Iwakuma was equally vague.
"Tough question," he said. "I can't give you an exact date. I want to come back as soon as possible and be pain free and be able to go 100 percent by the time I'm out there on the mound.
"One or two starts will get my feel back for my pitches, but I'll need to build my arm up to get to a certain amount of pitches. That will gradually tell as we go forward."
Iwakuma can draw some on his experience from 2012, his first season in the Majors. He arrived in camp with a shoulder that wasn't fully strengthened yet from an injury in his final season in Japan. The Mariners brought him along slowly, pitching him in long relief the first half of the season before moving him into the rotation on July 2.
He wound up going 8-4 with a 2.65 ERA in 16 starts that year, then carried that success over to 2013 when he was 14-6 with a 2.66 ERA and a club-record 1.006 WHIP.
"At that time, I didn't have that in mind," Iwakuma said of his slow start in 2012. "But I do realize it's a very long season after two years under my belt, so that kind of gives me a rough idea of how I need to prepare myself to be able to finish strong this year."