Crawford has been limited this spring because of inflammation in his left wrist, which was surgically repaired in the offseason.
"He is going to be hitting soon," Valentine said. "I don't know (specifically) when that is."
Valentine said Crawford has been working on his timing by standing in when Boston pitchers throw.
"The work that's gone unnoticed, I think, is going to pay dividends," Valentine said. "He has taken it upon himself to find a pitcher every time he's throwing to stand there and see (pitches). I think it's going to speed up his timing process."
There is no timetable for Crawford to return to game action, Valentine said. He previously acknowledged it was "probably not realistic" to think Crawford would be ready for Opening Day.
Carl Bleich is covering the Red Sox for ESPNBoston.com.