Having lost Thibaut Courtois to a serious knee injury, Los Blancos entered the loan market for Kepa, with the Spain international making the move to Bernabeu from Chelsea.
Andriy Lunin kept his starting role against Almeria on Saturday, with the Ukraine international now featuring in back-to-back games at the start of the new season, but Ancelotti has said that Kepa could make his debut in the clash with Celta Vigo next Friday.
"Lunin has played very well, like the game in Bilbao. We have confidence, the same as with Kepa. Sooner or later he will have to play, it may be the next game," Ancelotti told reporters on Saturday.
Los Blancos fell behind against Almeria, with Sergio Arribas making the breakthrough in the third minute, but Jude Bellingham's double sent the visitors ahead before Vinicius Junior made it 3-1 in the 73rd minute.
"Bellingham has settled in so well thanks to his maturity and his personality, as well as the fact he's been in Germany for the last three years. These are elements that have really helped him adapt well to La Liga and to our style. He's in great shape," Ancelotti added during his press conference.
"They caught us out with their first counter-attack, it was pretty much perfect. We could have dealt with it better but sometimes you have to give credit to their quality up top, it was a fantastic move and they got the goal. We didn't lose control and gradually worked our way into the game.
"We had a lot of chances and moved around really well, there are no fixed positions. That helps to make life tough for the opposition defensively. We have great variety and that helps us create chances.
"There is no fixed system at the moment. We started out with a low block and then when [Luka] Modric and [Eduardo] Camavinga came on, we played with two banks of four and felt comfortable.
"From a defensive perspective you struggle to control the flanks a bit more but going forward, this system gives you all sorts of options."
Ancelotti also praised Modric and Toni Kroos, with the latter playing 72 minutes of the match, while the former was introduced as a substitute in the 72nd minute.
Neither player is now a guaranteed starter for Real Madrid, with Federico Valverde, Aurelien Tchouameni, Camavinga and Bellingham seemingly ahead of the experienced duo in the pecking order.
"Kroos has played a very good game with the ball, he has had a lot of control. When Modric entered, he also handled the ball and the times of the game very well. The protagonism will be the same, but they may play a few minutes less. I don't know," said the manager.
Real Madrid also beat Athletic Bilbao on the opening weekend of the new La Liga season and will now be looking to make it three successes in a row when they head to Celta.