now (one's) cooking (with gas)
Now one is making progress or doing something right. That's how to do it, team! Now you're cooking with gas! Adjusting those parts made all the difference. Look how fast it goes! Now we're cooking!
Now you're cooking (with gas)!
Inf. Fig. Now you are doing what you should be doing! As Bob came to the end of the piece, the piano teacher said, "Now you're cooking with gas!" Tom (painting a fence): How am I doing with this painting? Any better? Jane: Now you're cooking. Tom: Want to try it?