The striker - a £3.5million summer buy from Watford - could not hit a proverbial barn door in his first six outings.
But his cool opener at Wolves was his third goal in as many games.
And Allen, who also registered his first Premier League strike, said: "It's fantastic for Danny.
"Not many people could believe he didn't find the back of the net in his opening games for us.
"We never doubted the goals would come as we've seen him day in, day out.
"You could see today that was another fantastic performance from him.
"When you see how he finishes goals in training, you know he will take that on to the pitch and score regularly."