I rode a 300km at 0.77, on a 1,000km event I did say 1 at 0.72, day 2 at 0.62 and day 3 at 0.60.
My honest advice would be follow your training plan. Arrive fresh on the day and take it easy. Enjoy the ride, company, scenery etc. Glance at your power occasionally to make sure you aren’t over doing it especially earlier on. Hope you have a great day 