Markakis is with the Orioles in Atlanta for their three-game series. Showalter said Markakis can already participate in most baseball activities.
"He's doing just about everything but hitting," Showalter said. "[Friday is] basically when he can start thinking about hitting and progress from there."
Markakis broke the bone in his wrist on a slide in mid-May and tried to play through it. But ultimately, he was forced to undergo surgery to remove part of the bone and go on the DL for the first time in his career.
Markakis is hitting .256 with eight home runs in 50 games this season.