Conte is recovering after undergoing a gall bladder surgery last month but Spurs have done well in his absence with Stellini on the touchline, moving up to fourth in the Premier League.
Spurs play away at Championship (second-tier) side Sheffield United in the FA Cup on Wednesday, a game that comes too soon for Conte.
"At the moment we're waiting for Antonio to come back but Antonio is still here because we work with him from here and we speak a lot," Stellini told reporters.
"I think this week he'll be back. He's not in charge for this game, but our doctor decides the right moment for Antonio to be back.
"It's a question for our medical department because they check with the doctor who did the surgery, they check today every day for the right day for Antonio to come back and I think it will be this week."
Spurs were knocked out of the competition at the same stage last season by second-tier opposition when they lost 1-0 at Middlesbrough and Stellini said Wednesday's game at Bramall Lane would not be easy.
"We have to progress, we have to try to win the game. It's an important competition, we take seriously all the competitions and we want to follow our momentum and we want to bring the same energy we had in our stadium to an away game," he said.
"We will pick the right team to play a great match and we can win also by making some changes. We completely trust all the players we have so we can make changes and nothing has to change.
"Last season we knew very well that we were disappointed after the match in Middlesbrough."
Stellini also said there were "no fresh injuries" with the club set to name the same squad that beat Chelsea 2-0 in the Premier League on Sunday.
