United completed the signing of the 22-year-old midfielder from Brighton & Hove Albion in a deal worth around 60 million pounds ($81.48 million), with further add-ons, this week, but the Cameroon international will have to wait for his debut.
"He's got a little ankle issue so maybe a couple of weeks or so, maybe three weeks," Carrick told reporters on Friday.
"But we knew that before, so it's no major issue. It'll be great to have him when we can."
Asked whether Baleba could return before the international break, Carrick added: "We'll wait and see. We're hopeful, but I don't want to put any deadlines on it just yet."
Carrick also provided a positive update on Mason Mount, saying the midfielder has returned to training after being forced off during United's 1-1 pre-season draw with Paris Saint-Germain.
However, Amad Diallo remains unavailable after suffering an injury in training.
"Amad won't be involved this week. He'll be out for a little bit longer," Carrick said.
United will be looking to bounce back in their first home league game after suffering a 2-0 defeat at promoted Hull City in their season opener.
"First home game of the season is one we look forward to," Carrick said.
"We're massively looking forward to the game. We had a setback last week and we want to get back to playing well and winning football matches."