Santana, who underwent Sept. 14 surgery to repair a torn anterior capsule in his left shoulder, is due to throw 45 pitches for Class A St. Lucie against the Daytona Cubs.
That activity starts a 30-day clock for Santana to be activated, so he appears likely to be back in the majors in late August barring any setbacks.
Santana threw a bullpen session Sunday for the major league staff in Miami. He threw a three-inning simulated game last Friday at the team's complex in Port St. Lucie, Fla.
"I felt good overall," Santana said about Sunday's session. "I think all the work that we have been doing is paying off. The way I'm feeling right now, I'm getting closer."
Adam Rubin covers the Mets for ESPNNewYork.com.