The Spain international suffered the injury during a King's Cup quarter-final second leg against Valencia last month when defender Alvaro Arbeloa accidentally kicked his hand while trying to clear the ball.
It was initially feared that Casillas might be sidelined until the end of April.
"I am getting better all the time, about halfway there," he said at a promotional event in Madrid. "There is a month to go.
"I will have to make a bit more of an effort to regain the mobility I had before," he added. "But I want to return as it's worse being away from the pitch than being able to play."
Real brought in Diego Lopez from Sevilla as cover for Casillas and he is likely to start their March 5 Champions League last 16, second leg at Manchester United.
The teams drew 1-1 at the Bernabeu in the first leg.