After four rounds, Sunderland have just one point and are last in the table but Di Canio believes his team have a big opportunity to move above 19th-placed West Bromwich Albion when the bottom two sides clash at the Hawthorns on Saturday.
Fletcher will be key to Sunderland's chances, according to Di Canio, with the 26-year-old Scottish striker still working his way back to full fitness after an ankle injury meant he missed the opening two matches of the season.
"He has the killer instinct in the box that we need," Di Canio told The Mirror.
"But we have a methodology with our players and we won't play him if he is not sharp enough.
"We want Fletcher to be sharp for six or seven months, not just one or two. Consequently, we will do what is best for the season as a whole, not just the next two of three games."
Fletcher came off the bench in Sunderland's third game of the season and scored in the second half, while he started last week versus Arsenal but failed to get on the scoresheet.
Sunderland have scored just three goals this season with only West Brom (one) and 16th-placed Hull City (two) having managed fewer.
Midfielders Emanuele Giaccherini and Craig Gardner have scored Sunderland's other goals but despite his team's struggles up front, Di Canio will not rush Fletcher if he is not ready to take on West Brom.
"He (Fletcher) scored an excellent goal against Crystal Palace but we have to remember he has been out a long time and not had the benefit of a full pre-season," Di Canio said.
"We cannot expect him to be consistent immediately.
"When you come back from a long injury, adrenaline helps you a lot (but) players are not machines.
"We have to handle him sensibly and he has done a sort of mini-pre-season with Claudio Donatelli but not had the double sessions of other players."
Fletcher top-scored for Sunderland last campaign with 11 goals.
