The righty, fresh off a solid bullpen session, will throw batting practice before Boston's game at Texas on Wednesday.
Bailey underwent right thumb surgery on April 4, the day before the season started.
Another key reliever is also on the mend. Righty Scott Atchison, who was probably the most consistent pitcher on Boston's staff in the first half, will start a Minor League rehab assignment on Friday. Atchison went on the disabled list on July 15 with tightness in his right forearm.
Valentine isn't sure where Atchison will pitch that day. Triple-A Pawtucket and Double-A Portland are both on the road on Friday, but Class A Lowell has a home game.
It sounds like Atchison should be ready to return to the roster around the time the Red Sox open their next homestand -- on July 30 against the Tigers.