There is a reason for the hips back first.
It is mainly a cue to remind you to push your hips back and down.
The majority of squat form checks revolve around people bending at the knee first and then dropping straight down with no rearward movement of the hips.
The rearward movement of the hips allows for tension to be built in the hamstrings.
If the hips are shoved back at the bottom of the squat it is easier to use hip drive to lift out of the hole.
When learning to squat, it is more beneficial to 'get' the posterior chain involved, the hamstrings and hip drive sorted first before worrying too much about knees.
I find if you think about breaking the knees to much, you end up forgetting to shove the hips back.
Remember learning to drive a car? You have to worry about looking, mirrors, steering, speed,accelerator, brake, clutch, gears etc all at the same time - pretty confusing until you eventually 'get' what you are supposed to do.
A bit like squatting really.
In essence though, knees and hips break together, with knees being fixed in the first half of the descent.
Starting Strength is worth the money spent.
