The Blues ranout 5-2 winners on Saturday.
Calvert-Lewin said, "We started a little bit slow, West Brom hit us on the break. We struggled to get it right.
"But then it was a nice day all round for myself, my first hat-trick. A good team performance.
"You look at the quality we have on the ball, it was important we utilised it with the extra man. We penetrated when we needed and I was happy to be in the box to tap them in.
"Carlo Ancelotti is on me every day for first-touch finishes and to be in the box, in the right areas. It's nice to know what I'm working on in training is coming off on the pitch.
"It's always nice when James Rodriguez has played at the highest level and he's settled straight in. It's not been too difficult for him. He's creating chances for me.
"It's important not to get carried way. We're taking it game by game. I need to keep taking care of business here."