Fernandez entered his 24th start against the Dodgers on Monday night at Marlins Park at 139 2/3 innings.
No firm date has been set.
But basically, the club is projecting its shut-down date based on an average of seven innings per start. If he indeed can go seven innings per outing, his final start would be on Sept. 4 against the Cubs at Wrigley Field. That's if the Marlins go with him every fifth game from this point forward.
At seven innings per start, he would reach 167 2/3 on Sept. 4. If the club decided to give him an extra day, he could finish up on Sept. 6 at Marlins Park against the Nationals.
"We set that deadline for a reason," Miami manager Mike Redmond said. "It's to take care of him and protect him. We realize this is a special kid who we want to keep healthy and have pitch for a long time."
Fernandez has enjoyed a terrific season, pacing rookie pitchers with at least 15 starts in ERA (2.45), opponents' batting average (.190) and strikeouts (149) entering Monday.
Fernandez is on pace to break the Marlins' rookie strikeout mark of 166, set by Scott Olsen in 2006.
The hard-throwing right-hander -- along with Dodgers outfielder and fellow Cuba native Yasiel Puig -- is a strong National League Rookie of the Year Award contender.
"When you set that deadline in Spring Training, you don't know how that's all going to shake out," Redmond said. "He's gone out and pitched great. For him to be in the situation he's in is tremendous.
"At the same time, too, I don't think guys always focus on the awards. They focus on doing their job. When they do their job, they're rewarded with accolades -- Rookie of the Year, MVP or whatever it is."
Fernandez's story is well documented.
He made the leap from Class A to the big leagues at the start of the season. He logged 134 innings in the regular season in the Minor Leagues a year ago.
In 2012, Fernandez made his last start during the championship round of the Florida State League playoffs on Sept. 9. He worked five innings that day in Class A Jupiter's victory over Lakeland.
"He's definitely done his job," Redmond said. "If I had to pick, I'd pick him [Rookie of the Year], for sure. But he's definitely at a disadvantage when you're talking about the Dodgers and the Marlins. For us, he's definitely our Rookie of the Year."