The right-hander has been on the disabled list since June 6.
If he's able to play catch this week, he hopes to progress to bullpen sessions next week, while remaining on his original timetable of a return in four to six weeks.
"I'm able to move around a whole lot better than I was a week or so ago," Peavy said. "I don't really feel it much in my normal day activity. I'm hopefully getting better. I've been moving around, been doing some shoulder stuff at home. Hopefully when I start playing catch, we won't have any setbacks."