The teenager star started in the Carabao Cup game against Reading. He scored a stunning 30-yard goal to help his team win 2-0.
And he believes he made the right decision for his development by joining the Premier League outfit. He left West Ham for the club.
"I am really happy with my performance and happy that the manager gave me the chance to start the game. I am even happier with the goal and couldn't wish for a better debut," Quina said to the Watford Observer.
"I could have gone to different, bigger clubs but personally I think I need to be where I am going to get first team experience. I think Watford is the best place for me to be right now."