Some sort of flat converse like shoe is ideal. A singlet (leotard) is mandatory, LiE bought one more recently than me. Although my glutes may rupture mine now actually...
Definitely don't do 531 up to the comp!
It gives you terrible prep for handling lower reps sets, which is sort of important for a powerlifter
Easy basic prep:
Next week:
Work up to an absolute 3 rep max. Try to get a few sets around this weight, aim for 3. This will be for each lift on different days. Normal amounts of assistance. The max weight you get here will be your opener, but obviously this only counts if the reps are comp legal. Oh yeah, start getting commands NOW. This is the one thing you are almost guaranteed to mess up. Practice practice practice.
Week after:
2 rep max, 3 sets again. Do not fail a rep if possible. Slightly reduced assistance
Week after (2 weeks before comp):
Work up to at least 95% for 1 rep on each lift on a different day. Again, try not to fail.
Week before comp:
Monday - work up to your openers. Do nothing else
Weds - do a couple of sets of very comfortable bench doubles. NOT AT MAX. Maybe warm up for squats and deads but don't do any work sets at all.
Friday - nothing
Sunday: Comp Day!
Plan some food for the day. Nothing too heavy or weird either. Don't forget any kit!
Make sure your openers are absolutely guaranteed. You win no prizes for opening too heavy. It NEEDS to be an easy weight.
2nd attempt should be almost your max.
3rd attempt should be your PB, or slightly more if it's feeling good.
DO NOT BE A RETARD WHEN PICKING YOUR WEIGHTS. Lifting in a comp is VERY different to lifting in a gym. Do not expect to PB.