All these guys/girls have said open with a weight you can do for 2-3 reps. That with a little basic gym math is 225kg. Not close to your all time best.
Get COMFORTABLE
Get CONFIDENT
Get COCKY
1st attempt 225kg
2nd attempt 240-245kg
3rd attempt go for a PR
If you haven't used a DL bar before get into the warmup room and have a play to get used to it. Grip wise it shouldn't be a problem.
I like Brandon Lilly's approach*
1st attempt - get a lift in, probably 90-94% of your max
2nd attempt - go for a pb, doesn't have to be a huge one, 2.5kg is enough
3rd attempt - 105-115% depending on how the 3rd felt
*going off his meet results/attempts that I've seen over the last 12 months this isn't exactly always how he takes attempts, but he's quoted as saying it is what he "likes to do"
As for comp tapering etc.
Leading into ProRaw, Emma took he 3 deadlift attempts off mats about 6 weeks out, then just did doubles and triples with 50-60%, with the final training session being 7 days out and hit a 17.5kg comp PB.
Squat went heavy 14 days out, 60-70% for doubles 7 days out which resulted in a 10kg PB
Like the others have said though, 99% of the hard work is done 4+ weeks out. The last month is more about how
you feel you need to get ready for competition.