Rooney completed his switch to the MLS side last month after just one season back with his boyhood club, ending a 16-year stay in the Premier League in the process.
DC United will take on Vancouver Whitecaps on Sunday morning, and Olsen suggested that the 32-year-old would be involved in some capacity.
"He's looked very, very sharp in training. He's fitting in with his teammates and we're looking forward to incorporating him in some way," Olsen told reporters.
"Whether he's in behind a lone striker or he becomes the lone striker, a lot of that depends on the game and the situation in the moment. We know his versatility but we also know he's scored a few goals in his day, so it will be a balance of that.
"It will take some time to figure out what is best, it is still a group and there are relationships around him, and we need to work out what will be best as a whole."
DC United currently sit bottom of the MLS Eastern Conference.