The Argentine striker came off the bench to make a goalscoring cameo in City's 5-0 third-round replay victory on Wednesday, as he continues his rehabilitation after a calf injury.
And Aguero was delighted at being back in the squad, and targeted reaching full fitness in plenty of time for the first leg of City's UEFA Champions League round of 16 clash with Barcelona on February 16.
"I couldn't wait to come back," he told the club's official website. "It's been a great recovery. I am very happy for the goal and also happy for the warm welcome of my team-mate and fans.
"And also, I'd like to thank the medical staff and the physios who did a great job.
"I trained with the team on Monday for the first time and today (Wednesday) I played some minutes to start bringing myself back on form and find my pace to play in such a fast football game.
"Maybe in a week I'll be on top form. Obviously, the more you play the better you feel.
"I hope I can play a little bit longer on Saturday and take it step by step.
"Against Barca I'll be ready. We still have time and first we have to think about the next Premier League games which are very important, and then we'll think about Barca."
Aguero's absence has barely been felt at the Etihad Stadium, with Edin Dzeko and Alvaro Negredo stepping up to the goalscoring plate.
And the former Atletico Madrid man believes the team is getting better all the time.
"I think we are doing very well," he added. "We have improved a lot since the beginning of the season.
"We must keep working like that. We are all playing very well.
"We are building a great team and need to continue trying to score more goals."
