Another good indicator for where to pinch before you ever see flower stalks is when you start to see the little leaves forming in a tight diamond pattern. Hard to describe, but take a look here:
(from
https://roundrockgarden.wordpress.co...l-growing-tip/)
I have to pinch this way because it takes no time at all for my basil to start flowering in the Central TX heat. It's very easy to do, just check for that leaf pattern each day and pinch it off with your fingernails. Makes your hands smell nice, too.