First competition question

[somersetred]

Hi all - first time posting.

I have a question, I'm doing my first comp, it's fairly simple

heaviest 30m Farmers walk (Currently 200kg)
5 rep max Bench Press (Currently 110KG)
5 Rep Max Back Squat (Currently 140KG)
1 Rep Max Clean (Currently 100 KG)

Now we have 15 mins per exercise to find our max reps however what would you start on? I have noticed say If i start on 20 percent and work my way up my body is shattered by the time I get to my max and I struggle to lift more.

Would you start on say 75 percent of the max lift?

I'd be warming up with a very light workout/bar

Appreciate your help, I have only been lifting for about 2 years and absolutely love it!

The comp is in October so any tips from now until then please do let me know. There won't be ridiculously big lifters in this as most of our big lifters in the gym do national comps, this is a in house thing :-)