No don't do that. If you're half squatting 265 you won't be able to full squat that much. Just warm up normally and find a weight you can do for 3x5 which allows you full depth and good form. Then progress up from there.
This!
If i were you, since you are doing starting strength, i would do what Mark Rippetoe suggests himself to find your starting weight :
The first set of squats begins at 45 lbs (an empty barbell) and a set of five is performed. If this is completed easily with the trainee's best form, ten pounds are added to the bar for the next set. If bar speed does not slow and form does not break down, ten more pounds are added to the bar and another set is performed. This process continues until either form begins to falter or the bar speed slows more than the preceding sets, whichever comes first. This is the trainee's starting weight. Once this occurs the trainee rests and performs two more sets at this weight, for a total of three sets of five reps (3x5) at the starting weight.
Actually , i was you a couple of weeks ago , i had form and depth issues so decided to take that step back to fix them , ended up starting 50lbs lower than were i was.
Also , FILM EVERY SESSION. You might think that you have your issues fixed but only the video and people who know their stuff will tell.
Oh , and you , that stated that you do solid form ATG squats and the couple of guys that saw you and said your form is good are NOT included in the people who know!
Edit : The quoted text is the guidline for the athlete's first starting strength workout ever , hence the 10lbs increment. You can use more than that, i would suggest 20lbs increments and i would expect your speed to go down of your form to break down somwehere in the high 100's. Suck up your ego and go quality over quantity.
That's all from me, cheers.