My recommendation would be dial in form with an empty bar so you are hitting good ROM, at or below parallel. Then, progress up, 5x5, each workout goes up by 10lbs. So, a simple progression would be 45lbs (bar) 5x5, 55lbs (bar+5 lb on each side) 5x5, etc. Faster progression is tough to maintain, most times people get too sore and quit.Legs.......5 sets of 20 body weight squats and I can't walk for a week due to leg muscle pain. It simply never goes away. Each week is as painful and brutal as the next....hence why I don't train legs. It's completely debilitating and does not fade or improve over the weeks. TheraGun is a Torture Device. It's simply ZERO fun. I can run or walk on the treadmill, TheraGun or whatever. The lactic acid never leaves and my legs are extremely painful for 7 days. Does not leave me wanting to do it all over again once I can finally walk normally.
Also, training legs with weights heavy enough to make you strong is difficult and you will be sore. There is no getting around this. My personal best is 5 reps @ 2x BW, that causes damage. Suck it up.