After many years of experience and many meets where i didn’t get what I wanted I now advocate the following. Your heaviest squat should be 21 days out, say 95% for some doubles or triples. The following week accumulate some volume say 5 doubles or triples at around 90%. The Monday before the meet stay at around 75% for some triples. The Wednesday before the meet do some singles with 135.
Now regarding your openers, I like a light opener. Light meaning one which I know I can make no matter what, say about in between my heaviest 5 and heaviest 3 for that cycle. Notice I didn’t say RM becasue only the current cycle is relevant. Make sure the opener is a weight you can SINK and get three whites with. This will et the tone for the squats. I found through all the years competing that the highest total usually went to the lifter who:
a. Had the highest squat
b. Made all three squats.
The reason you don’t actually lift your opener in the gym (go lighter or heavier) is so a gym failure can be rationalized. If you plan on an opener of 400 you would take 395 or 405 as a gym lift. If you make 395 easily, you know you can do more. If you grind and fail with 405 you can convince yourself that you can make 400. If you fail with 395 you say you had a shitty day. The bottom line is you did not fail with 400.
As for the second attempt, I would plan on it being 5-10 lbs below your anticipated third. This leaves you some cushion and allows for fucked up meet conditions. If you fail on a technicality you can repeat with confidence. If you make it you can always go up.
In 17 years of competition I never failed a squat for any reason but a heavy third and only bombed once due to flu induce weight loss one week out.