The Black Cats' new striker, 25, made his Premier League debut at Swansea and marked it with two good finishes.
The Scot was delighted after slapping in a transfer request at Wolves to clinch a protracted switch.
Fletcher said: "It took a while for me to get the deal done but I am glad I am here.
"It has taken a bit of pressure off me getting the goals straightaway.
"But there's no pressure from the money, it doesn't bother me."