Wheeler, who underwent Tommy John surgery in March 2015, is due to begin a minor-league rehab assignment on Saturday, general manager Sandy Alderson said.
Wheeler threw a simulated game on Monday in Port St. Lucie, Florida, as the final step before entering official games. His fastball sat at 90-93 mph, according to Alderson.
A rehab assignment lasts a maximum of 30 days, so Wheeler's return should come shortly after rosters expand on Sept. 1.
Wheeler suffered a pair of setbacks this year. Doctors performed surgery in April to remove an undissolved stitch from his original Tommy John procedure. And Wheeler required a cortisone injection in June for nerve irritation.