The £5million man is yet to score for his new club, but O'Neill is hoping the 27-year-old's time is fast approaching.
He said: "Danny has scored goals in this league, so once he gets up and running and off the mark, the rest should follow.
"I'm sure that's exactly what he's looking for. It would have been great if he got off to the start that Steven Fletcher got here. It would have settled him down.
"But now there's every opportunity for him to go and do well."