To be honest, its not a huge issue (and it wont affect your quad balance if this is where you are coming from). The thing about squats is that it is not really a quad-centric exercise. What IS important is strong posterior chain engagement, and locking out the hips at the top.
Most involved with heavy squat do lock out everything at the top, then take a breath, drop, then exhale on the way back up.
This is a good tempo guide, increases rep by rep focus, and also, lungs full of air on the way down helps stabilise the movement in some ways.
You are not a bodybuilder- stop obsessing about your quads, its all about posterior chain and your core now