SCOTTSDALE, Ariz. — David Dahl is restless but realistic.

The injured Rockies outfielder is making slow progress as he recovers from pain in his mid-back that was eventually diagnosed as a stress reaction to his sixth rib. He definitely will miss the start of the season and could be out most of April.

Dahl is now softly tossing a ball and doing some light cardio work and some agility drills. He is scheduled to have a CT scan Friday to determine his progress.

“It’s tough to sit, for sure,” Dahl said Sunday. “But I suppose it’s better for it to happen now instead of at midseason. The good thing is, it doesn’t hurt now.”

The Rockies are offering no specific timetable for Dahl’s return. Optimistically, he could be back on the playing field before the end of April, but there are no guarantees. Dahl knows for sure that he’s going to miss opening day next Monday at Milwaukee, as well as the home opener at Coors Field on April 7.

“I’m disappointed, for sure,” he said. “It would have been my first opening day, but it is what it is. I have to get fully healthy now so I can help the team later.”

Dahl, who turns 23 Saturday, arrived at spring training as the favorite to win the starting job in left field and build off an excellent rookie season. The 10th player selected in the 2012 draft, Dahl hit .315 with seven homers in 63 games last season, his first in the majors. He played in just two Cactus League games this spring, going 0-for-4 with a walk.

First base set. The Rockies added Mark Reynolds to their major-league roster Sunday, setting up the veteran to start opening day at first base. Reynolds signed a minor-league contract in the offseason to be a backup to Ian Desmond and provide a powerful bat off the bench. But Desmond (broken hand) will miss several weeks. “We informed him late last night that he made the team,” Colorado manager Bud Black said. “Even going back to when he signed, he wanted to be a Rockie. And things have worked out.”

Footnotes. Right-handed reliever Greg Holland is scheduled to pitch Monday and Tuesday, his first back-to-back days since returning from Tommy John surgery. … Right-hander Harrison Musgrave, a starting pitcher through spring, is scheduled for two or three innings of relief Monday and Friday. The Rockies have discussed using a starter in the bullpen to begin the season. … Left-hander Kyle Freeland will start Monday and Saturday’s Cactus League finale. He is likely to begin the regular season in the Rockies rotation. Antonio Senzatela starts Tuesday. He, too, is likely for the rotation.